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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5344_Библиотеки_им_академика_М_И_Перельмана.pdf
Introduction to Pharmaceutical Biotechnology, Volume 2 (Second Edition)
questions are raised by its widespread use in cancer, genetic diseases, and other
therapeutic fields. Consent, anonymity, privacy, and secondary use of data are all
critical ethical issues. When dealing with human samples, frameworks are urgently
needed to control data exchange, access, and general management of proteomic data
[98]. Proteomics data is growing at an accelerated pace, which brings both benefits
and problems. Robust data management systems are necessary for processing largescale proteomic data, often incorporating biological materials like cells, organelles,
or fluids. To further research in this discipline, these platforms must guarantee data
integrity, accessibility, and repeatability. Additionally, discovering new disease
biomarkers and possible treatment targets depends on efficient data management
techniques [99]. The advancement of proteomics, the confirmation of discoveries,
and the promotion of joint initiatives depend on data exchange. However, there are
moral concerns when dealing with a human being’s data. Issues include handling
secondary data uses, keeping data anonymous, and getting informed permission
from participants. To solve these problems, we need robust protocols and platforms
for exchanging data which comply with applicable regulations. Mainly, when
working with proteomic data obtained from human samples, privacy is a significant
problem. It is essential to protect the privacy and confidentiality of the people whose
data is being shared or examined. This calls for reliable de-identification methods,
safe data transmission and storage protocols, and stringent access restrictions.
People should also be fully informed about the procedures to preserve their privacy,
who will access their data, and how it will be used [100].
Bioinformatics resources and data repositories, alongside open-source platforms
for proteomic analysis, are quintessential for the proficient management, analysis,
and sharing of proteomic data. Proteomic data, being large and complex, necessitates the use of specialized bioinformatics resources and repositories. Many
publicly available data repositories support protein-related information management, hypothesis generation, and biological knowledge discovery. Key characteristics of these repositories include well-documented resources, peer-reviewed or
selected by reputable consortia like the UniProt consortium, and well-maintained
databases. The guidelines for data submission, file format standardization, and
submission systems are provided by repositories such as ProteomeXchange. These
repositories are further categorized into archives that are responsible for data
submission and resources for peptide and protein identification. These resources
may include information about variants, mutations, or PTMs [101]. Repositories
store a wide range of data types and use a variety of data submission mechanisms.
They support numerous formats and provide data mining and visualization
capabilities, often enumerating the data contents of model organisms for each
resource. On the other hand, the public deposition and storage infrastructure for
MS-based proteomics data lags behind that of genomics. The intrinsic complexity of
proteomics data and the multiplicity of data types and experimental procedures
involved are ascribed to this difference. These present difficulties in standardizing
data input and retrieval protocols, impeding the creation of strong archives similar
to those created in genomics [92, 102].
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8.14.1 Open-source platforms for proteomic analysis
Open-source platforms facilitate the analysis and interpretation of proteomic data.
Various tools and packages are available, tailored to different aspects of proteomic
analysis.
• Tidyproteomics aims to streamline the analysis of quantitative proteomics
data using MS through data standardization and facilitating data exploration
across different platforms, catering to various R programming skill levels
[103].
• Visualize is a free, multi-functional tool for proteomics data analysis, offering
compiled executable files for Windows and Mac OS X alongside the complete
PERL source code [104].
• Amica is web-based software that simplifies high throughput data analysis in
quantitative proteomics, particularly for users with limited background
knowledge [105].
• ProteoWizard facilitates the development of proteomic data analysis tools
and format conversion through an open-source software platform [106].
• Informed-Proteomics is a software suite targeted at top-down proteomics
analysis, encompassing a range of tools like an LC–MS feature finding
algorithm (ProMex), a new database search algorithm (MSPathFinder), and
an interactive results viewer (LcMsSpectator) [107].
• MaxQuant is a comprehensive software suite for analyzing large mass
spectrometric datasets, mainly aimed at high-resolution MS data analysis
and capable of handling extensive proteomic datasets [108].
• OpenMS is an open-source framework offering tools for processing MS data,
including proteomic and metabolomic data analysis [109].
• PeptideShaker is an open-source software that interprets proteomics identification results from multiple search engines [110].
• SearchGUI is an open-source graphical user interface for configuring and
running proteomics identification search engines [111].
• Skyline is a free and open-source program that helps develop quantitative
methodologies and analyze mass spectrometer data, making it ideal for
focused proteomics experiments [112].
• The Perseus software architecture allows for the interactive study of massive
datasets, making it ideal for proteomics research [113].
• Pyteomics is a set of Python modules for analyzing proteome data, including
parsing proteomics data files, manipulating data, and doing statistical
analysis [114].
8.15 Cellular and molecular dynamics
Proteins are fundamental entities in molecular biology, orchestrating the functions
of organisms. Their behaviors are far from static; instead, they exhibit dynamic
characteristics essential for their functionality [115, 116]. Protein dynamics are
intimately intertwined with their functions. The 3D structures of proteins are
foundational to their function, but the dynamics, including conformational changes,
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enable proteins to interact with other molecules and carry out their roles [115]. The
dynamism of proteins spans a field from fast vibrational states to folding/unfolding
events. These conformational changes are crucial for many biological functions,
allowing proteins to adapt to different molecular interactions and cellular environments [116]. The protein folding process, where a protein acquires its functional
structure from a linear chain of amino acids, is a fundamental aspect of protein
dynamics. The correct folding of proteins is crucial as it directly impacts their
functionality. On the other hand, protein misfolding is associated with a broad range
of diseases and may lead to dysfunction when proteins do not acquire or maintain
their proper structure. Plaques occur in the cells of many neurodegenerative diseases,
including Parkinson’s and Alzheimer’s. These plaques may be the result of misfolded
proteins aggregating and forming. Numerous substances, including other proteins,
nucleic acids, and small molecules, may interact to affect the folding and misfolding
of proteins. The cellular environment, which may be very important due to
chaperone proteins, may also be very important in ensuring correct protein folding
or reducing the effects of protein misfolding [116].
8.15.1 Molecular mechanisms of protein function
Protein function is inherently complex, regulated by a variety of molecular
mechanisms. Protein kinases are enzymes that modify the structure of other proteins
by adding phosphate groups (a chemical modification) to them via phosphorylation.
In contrast, phosphatases are responsible for the elimination of these phosphate
groups, which is referred to as the dephosphorylation process. A proper balance
between the activity of kinases and phosphatases is crucial to properly functioning
proteins and, by extension, cells [117]. When a molecule, also known as a ligand,
attaches to a specific site on a protein, the protein’s function may be dramatically
changed. This region, also known as the ligand-binding site, often has a cavity
formed by a particular arrangement of amino acids. The protein’s function may be
altered due to conformational changes induced by ligand interaction.
Phosphorylation, in which a phosphate group is transferred from a donor molecule
(such as ATP) to a protein, is an example of a reversible process. The protein’s shape
may vary due to this insertion, affecting its function by changing its interactions with
other proteins or subcellular localization [118].
8.15.2 Protein degradation pathways
Protein degradation is a process that cells go through to maintain their protein
homeostasis. Proteasomes are protein complexes that use the process of proteolysis
to break down damaged or superfluous proteins. A chemical process called
proteolysis breaks down peptides into their constituent amino acids. A significant
pathway called the Ubiquitin-Proteasome System, or UPS, involves the proteasome
first destroying the proteins marked for death by the ubiquitin protein, which is a
small protein. Lysosomes are membrane-bound organelles that contain enzymes to
degrade waste materials and cellular debris. They are responsible for degrading
long-lived proteins, insoluble protein aggregates, and even entire organelles through
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processes like endocytosis, phagocytosis, or autophagy [119]. The endosomal pathway is part of the lysosomal pathway, where proteins are sorted and sent to
lysosomes for degradation. Post endocytosis, some cell surface proteins are recycled,
while others are marked for degradation and sent to the lysosomes [119].
8.15.3 Post-translational modifications and protein function
PTMs are crucial molecular alterations that occur on proteins after their biosynthesis, significantly affecting their function, stability, and interactions with other
cellular entities. PTMs refer to modifications on proteins’ amino acid side chains
occurring after their biosynthesis. Over 400 different types of PTMs have been
identified, each potentially impacting various aspects of protein function. These
modifications are indispensable molecular regulatory mechanisms arranging diverse
cellular processes [120]. Protein PTMs significantly expand proteins’ capabilities by
adding new functions and dynamically regulating protein activity. They are able to
do this by adjusting the interactions between molecules. Reversible attachments to
nucleophilic functional groups on amino acid side chains are the common conception of protein-tyrosine modifications, with the polypeptide backbone remaining
mostly unchanged [121]. A key regulatory mechanism for managing protein
function, expression, location, and interactions with other biological components
is protein PTM. Proteins have amino acid residues that either have chemical groups
added to them or removed from them. Common types of PTM include phosphorylation, ubiquitylation, methylation, and acetylation. PTMs play a broad range of
biological activities, which serves as an example of their significance in molecular
and cellular biology [122]. PTMs need proteolytic cleavages, the formation of S-S
cystine bonds, and the formation of asparagine-linked carbohydrate chains. Each of
these events has a distinct impact on the protein’s function and structure [123].
8.15.4 Cellular signaling pathways
The proper functioning of cellular signaling is essential for the appropriate control of
cellular activity and the preservation of cellular integrity. In order to trigger a
reaction from inside the cell, signals must be sent from the cellular membrane to the
interior of the cell. Signaling pathways, like the Ras/MAPK and PI3K/AKT/mTOR
pathways, are implicated in many cellular processes and are often thought to be
involved in diseases like cancer [124]. The JAK/STAT signaling pathway is another
pivotal signaling route at cellular, molecular, and genomic levels, involved in
transmitting information received from extracellular signals to the nucleus, resulting
in DNA transcription and expression of specific genes [125]. A conserved repertoire
of intercellular signaling pathways enables communication between animal cells.
These pathways are well-studied from a molecular perspective, although an operational understanding to control cellular behaviors rationally often lacks [126].
Multiple cellular processes, including as proliferation, differentiation, growth, and
cell-cycle transition, as well as neurotransmission and pathogen-sensing, are
governed by cellular signaling [127].
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8.15.5 Proteomic analysis of signaling networks
The proteomic analysis of signaling networks involves studying the proteome to
understand cell signaling pathways and networks. Critical regulators of biological
activities, kinases, and phosphatases are integral parts of protein phosphorylation
signaling networks. Proteomics, inherently a systems science, investigates individual
proteins and their expressions and goes into the interplay of proteins, protein
complexes, signaling pathways, and network modules. This field has seen a rapid
accumulation of data in recent years [128]. MS has become an essential technique in
the research of several aspects of cell signaling since it can be used to identify and
quantify PTMs, characterize protein–protein interactions, and analyze changes in
protein expression. Progress in the proteomic technique, especially in computational
proteomics, has made it feasible to characterize a whole proteome quantitatively.
Stable isotope labeling of amino acids in cell culture (SILAC) and isobaric tagging
for relative and absolute quantification are two of the most widely used methods for
MS-based measurement of proteins and PTMs (iTRAQ). Hundreds of phosphorylation and acetylation sites have been accurately determined by means of highresolution quantitative MS. This has paved the way for both targeted functional
analysis of specific proteins and broader ‘systems-wide’ investigations. Global
signaling networks, as well as the dynamics of these networks in response to
different cellular perturbations, that have been illuminated by the use of highresolution quantitative MS bioinformatic proteomic data analysis may provide light
on the origins and evolution of signaling networks, as well as the global kinase–
substrate interactions [129].
8.15.6 Signaling pathway dysregulation in disease
Signaling pathways are intricately connected to numerous diseases due to their crucial
role in maintaining cellular function and communication. Dysregulation in these
pathways can lead to a multitude of diseases. Examples of factors that contribute to
the oncogenesis and heterogeneity of lymphoid malignancies include dysregulated
oncogenic signaling pathways and aberrant genomic changes. Disease pathophysiology may be better understood, and tailored therapeutics can be developed by focusing
on the underlying processes of these dysregulated signaling pathways and the potential
value of pathway-related biomarkers [130]. Furthermore, minor phenotypic changes
in signaling pathways are implicated in causing significant human diseases such as
hypertension, heart disease, diabetes, and various psychiatric illnesses. Such phenotypic remodeling alters the behavior of cells, disrupts their usual functions, and results
in disease. Specific signaling pathways, like the mTOR signaling pathway, play
intricate roles in cellular functions, and their dysregulation is associated with several
diseases, particularly neurodegenerative disorders [131].
8.15.7 Targeting signaling pathways in drug discovery
Targeting signaling pathways for drug discovery is a promising strategy for
developing novel therapeutics for various diseases. The Hippo pathway, for
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instance, has been explored across biological processes and diseases, and recent
studies have shed light on its potential as a therapeutic target in cancer, fibrosis, and
wound healing. Likewise, the Transforming Growth Factor-β (TGFβ) signaling
pathway, implicated in disorders like cancer, fibrosis, and inflammation, has
emerged as an attractive target for drug development [132]. The process of targeting
signaling pathways extends to identifying crucial strategies, targets, and opportunities in drug discovery, enabling therapeutics to be developed to modulate these
pathways for disease treatment. Recent advances in cancer drug discovery, for
instance, have led to the development of signaling-based cancer therapies. Synthetic
lethality is employed to target ‘undruggable’ proteins and treat drug-resistant
cancers by perturbing specific signaling pathways, thus highlighting the potential
of targeting signaling pathways in drug discovery [132].
8.15.8 Crosstalk between signaling pathways
Crosstalk between signaling pathways is a fundamental aspect of cellular signaling
networks, facilitating the integration and coordination of multiple signaling inputs
to ensure appropriate cellular responses. Molecular biologists and geneticists have
spent the better part of the past two decades dissecting intracellular signaling
networks in individual cells, revealing extensive crosstalk across crucial signaling
pathways, especially in animals. Despite the apparent integration of several signals
at gene promoters, reports of this crosstalk in plants are few [133]. One manifestation of crosstalk is observed in nuclear receptor signaling, where coupled nuclear
receptor-induced signaling pathways exhibit either a direct or an indirect interplay,
which could be additive or antagonistic. This crosstalk is essential for achieving
precise control over cellular responses [134]. The Mitogen-Activated Protein Kinase
(MAPK) cascades are well-known for the crosstalk between their constituent
classical signaling pathways, such as ERK1/2, c-Jun N-terminal kinase (JNK),
p38, and ERK5. These sub-pathways allow for the successive transmission of
phosphorylation events by transporting signals across a chain of proteins.
Phosphorylation events provide interaction and mutual influence across different
signaling pathways, guaranteeing accurate signal transmission and manipulation.
Cancer, which is characterized by the interplay of numerous signaling pathways to
either promote or hinder tumor formation, is a prime example of the importance of
crosstalk in the setting of sickness. Understanding the interplay between various
signaling pathways may help develop novel therapeutic approaches. For instance,
new avenues in the fight against cancer have been explored by exploring strategies to
build anti-CSC medicines that target the crosstalk between signaling pathways in
cancer stem cells (CSCs). The hope is that by adopting this approach, we may find
better ways to treat cancer [135]. Cells can now react correctly to disruptions in
homeostasis due to the development of crosstalk across signaling pathways. The
connections that are made between significant signaling channels offer a feedback
mechanism. This system makes it easier for cells to remain intact and enables a
coordinated response to various stimuli [136].
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8.16 Membrane proteomics
Membrane proteomics is a subdiscipline of proteomics, a larger area of research that
focuses on the detailed examination of proteins present in membranes. Numerous
cellular processes depend on these proteins, such as nutrition transport, bioenergetic
activities, cell adhesion, and signal transduction [137]. Due to the challenges of
solubilizing, isolating, and identifying membrane proteins, the area of membrane
proteomics has generally been understudied. Since it is estimated that more than
30 percent of all proteins in Nature are located in membranes, membrane proteomics
research has been mostly neglected. Recent developments in membrane proteomics
have made major contributions to our knowledge of the intricate relationships
between lipids and proteins that are necessary for healthy cell function [138].
8.16.1 Techniques for membrane protein analysis
Multiple methods and tools have been developed to investigate membrane proteins
and their dynamic properties. The use of computer modeling and machine learning
has been used to study protein membrane structures. In addition to extending to a
wide variety of structural properties, such as lipid interactions, allostery, and
structure prediction, these computational methods may be utilized to sidestep
challenges associated with experimental characterization [139]. The essentials of
building and evaluating membrane and membrane protein simulations have been
addressed. These simulations may be carried out by following the precise instructions provided in earlier sources. The three most common single-molecule techniques used on membrane proteins are fluorescence correlation spectroscopy, singleparticle tracking, and atomic force microscopy, and their principles are explained
here. These approaches have greatly aided the area of membrane protein research by
offering insights into the behavior of specific membrane proteins. Understanding the
structure and function of membrane proteins requires efficient production, solubilization, and analysis. The amphipathic structure of membrane proteins makes them
challenging to investigate, although numerous approaches have been devised to
circumvent this obstacle [140].
8.16.2 Membrane protein structure and function
Membrane proteins are essential to a wide variety of biological functions because
they act as conduits for information exchange between the inside and outside of the
cell. Understanding the relationship between membrane protein structure and
function is crucial for elucidating the function of membrane proteins in cellular
physiology. How a protein binds to the lipid bilayer provides a valuable categorization scheme for membrane proteins. Proteins in membranes may be classified as
either integral (crossing the whole membrane) or peripheral (associating with the
surface but not penetrating the membrane) [141]. Furthermore, membrane proteins
often have two regions: a hydrophilic portion that interacts with water and a
hydrophobic region that interacts with the lipid bilayer. Both of these areas aid the
movement of the protein across the membrane. The movement of ions and larger
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solutes across membranes, the promotion of intracellular communication, and the
catalysis of chemical reactions are just a few of the functions membrane proteins
perform. They are also engaged in cell adhesion, which aids in cell attachment to the
extracellular matrix or neighboring cells, and signal transduction, where they may
start intracellular signaling cascades in response to external signals. They aid in cell
adhesion by assisting cells in sticking to the extracellular matrix, and they may begin
intracellular signaling cascades in signal transduction [142]. The communication
between proteins and lipids is crucial to the membrane’s function. As a result, ion
transport and other membrane protein functions may be altered by the lipid milieu
in which they are embedded [143].
8.16.3 Membrane proteins in disease
Mutations or improper regulation of membrane proteins may result in a wide range
of disorders. Mutations in membrane proteins have been linked to a number of
diseases. One such mutation causes congenital hyperthyroidism and is designated
V509A in the thyrotropin receptor. Hereditary deafness, Charcot–Marie–Tooth
disease, and Dejerine–Sottas syndrome are also associated with mutations in
membrane proteins [144]. Diseases can also arise from misassembling membrane
proteins, where incorrect interactions in the folding and assembly of integral αhelical membrane proteins lead to functional aberrations. Membrane proteins play a
significant role in oncology, especially those regulating the proliferation of tumor
cells and affecting the immune response. Understanding the function and regulation
of membrane proteins can aid in developing novel therapeutic strategies for cancer
treatment [145].
8.16.4 Drug targeting of membrane proteins
Membrane proteins (MPs) are crucial targets in drug discovery due to their central
roles in cellular processes and interactions with the extracellular environment.
Membrane proteins are crucial drug targets across various fields of medicine due
to their many important functions, which include transport, signaling, and serving as
gatekeepers to the cell [146]. They are implicated in numerous human ailments and
can be accessed by small- and large-molecule drugs from their location at the cell
surface. The lack of reliable methods for creating functional variants of membrane
proteins has historically been a significant barrier in the drug development process
[146]. The amphipathic nature of membrane proteins, having both hydrophilic and
hydrophobic regions, complicates their analysis and targeting. Advances in targeted
protein degradation (TPD) technology, such as proteolysis-targeting chimeras
(PROTACs) and lysosome-targeting chimeras (LYTACs), have emerged as significant breakthroughs in drug discovery. LYTACs, designed to degrade extracellular
proteins, address some limitations of PROTACs, which are mainly restricted to the
degradation of intracellular proteins. Drugging previously undruggable membrane
proteins and modulating cellular signaling are now possible because of recent
technological advances. These developments enable the regulation of protein–
protein interactions, ion transport, and molecule transport in membranes, thereby
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increasing the number of potential therapeutic targets. Various strategies have been
employed in drug discovery targeting membrane proteins. For instance, strategies
for expressing, stabilizing, and formulating recombinant multipass MPs as potential
small molecule medicines have been suggested [147].
8.17 Subcellular proteomics
Subcellular proteomics is an area of study focused on understanding the protein
compositions within various subcellular structures or organelles of a cell. The
eukaryotic cell is segmented into several subcellular locations, some of which include
membrane-bound organelles and others that do not. Since proteins localize to
specific places to perform their functions, it is conceivable for many biological
processes to occur simultaneously. Understanding the functions of these subcellular
structures, as well as the cellular processes and disorders associated with protein
mislocalization, requires an understanding of the location, distribution, and abundance of the proteins contained inside. Hybridization techniques are only one of the
numerous methods developed to quantify cellular data. These techniques can
potentially advance our understanding of cellular structure and function by
facilitating research into organelle composition [148].
8.17.1 Organelle-specific proteomics
Organelle-specific proteomics investigates further into the subcellular level by
focusing on the protein compositions inside specific organelles. This approach
enables the identification of novel diseases and molecular mechanisms by utilizing
techniques to investigate specialized organelles like cilia, affinity proteomics,
genetics, and cell biology are all useful tools. For instance, tagging human ciliary
proteins helped establish a landscape of proteins, interactions, and complexes unique
to this organelle, illuminating hitherto unsuspected complexes and interactions that
are only present in the cilium. This detailed analysis linked various cellular
components and processes to ciliary signaling and proteostasis, discovering the
molecular mechanisms underlying ciliary diseases [149]. Imaging-based spatial
proteomics, which requires a proteome-wide library of affinity reagents, a complete
collection of cell lines expressing tagged proteins, and setups for high-throughput
microscopy, is one of the methodologies used in organelle-specific proteomics.
Organellar profiling is another approach that helps to create organellar maps
through proteomic profiling, providing a conceptual guide for understanding the
spatial distribution of proteins within organelles. In addition, low-abundance,
organelle-specific proteins may be better understood with integrated analysis of
data obtained from many organelles, which can show common molecular components engaged in coordination across distinct cell compartments [150].
8.17.2 Protein localization and trafficking
Protein localization and trafficking are integral to cellular functionality and
organismal health. Proteins must be correctly localized within cellular compartments to perform their functions efficiently. The trafficking of proteins ensures that
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they are transported to their correct locations post-synthesis. Certain proteins, like
G-protein coupled receptors (GPCRs), have their activity, trafficking, and localization regulated by interacting proteins. This regulation is pivotal for the proper
functioning of GPCRs and, by extension, the signaling pathways they are involved
in. Protein subcellular localization and trafficking studies, particularly those focusing on endomembrane system organelles, make use of current methodologies and
organelle markers. These approaches, however, have drawbacks when it comes to
studying protein colocalization [151]. Subcellular trafficking is greatly aided by the
PTM of proteins by palmitoylation. It plays a role in cellular protein location and
function. Measuring protein trafficking’sefficacy, kinetics, and processes may be
tricky. Protein trafficking across cellular compartments may be studied with the use
of a number of technologies that allow for the spatial and temporal monitoring of
protein distribution [152].
8.17.3 Proteomics of cellular compartments
The proteomics of cellular compartments investigates into understanding the protein
composition within different cellular locations. Understanding the subcellular
localizations and dynamics of proteins, or the spatial proteome, is essential for a
comprehensive understanding of cell biology. Mature proteome-wide analyses of
spatial cellular regulation have resulted from major advances in MS, microscopy,
and machine learning algorithms for data interpretation. A few of the features that
have come to light from the study include single-cell variations, dynamic protein
translocations, developing interaction networks, and proteins localizing to different
compartments [153]. Quantitative MS, via organellar profiling or interactomics,
may reveal subcellular protein networks, while high-throughput imaging can reveal
all proteins inside a cell or a compartment of interest in spatial proteomics. The
current approaches in spatial proteomics and transcriptomics are directly compared
in order to provide a comprehensive overview of the available tools. Among these
methods are those that rely on imaging and sequencing to provide light on the
location of proteins inside individual cell compartments [148].
8.17.4 Techniques for subcellular proteomic analysis
It is crucial to comprehend their distribution among the distinct subcellular
compartments to obtain insight into the function of proteins and the associated
cellular processes. Numerous alternative approaches have been established to
analyze the subcellular proteome, each of which comes with its pros and limitations.
Subcellular proteomes are often studied by performing cellular fractionation
followed by proteomic analysis. Biological components are initially divided into
subcellular proteomics according to the variations in their physical or chemical
characteristics. Proteomic methods are then used to assess the protein composition
of the isolated fractions [154]. Density gradient centrifugation is a dependable
method for achieving cellular fractionation. Cellular components are separated
using this centrifugation technique based on the buoyant densities of each component. Isolating organelles and other subcellular structures using this approach is
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