A fast and convenient MALDI-MS based proteomic approach: identification of components scaffolded by the actin cytoskeleton of activated human thrombocytes

Differentially expressed proteins in platelets derived from patients with hypertension

Hypertension (HTN) causes end-organ damage and is a major cause of morbidity and mortality globally. Recent studies suggested blood cells participate in the maintenance of HTN. Platelets—anucleated cell fragments derived from megakaryocytes—exert diverse functions, including their well-characterized role in the formation of hemostatic clots. However, platelets from patients with HTN exhibit altered membrane lipid and protein compositions that impact platelet function and lead to formation of aggregates and vascular obstructions. Here, for the first time, we have identified, by proteomic analyses, the most relevant 11 proteins that show the greatest difference in their expression in platelets derived from patients with HTN, in comparison with those from normotensive individuals. These proteins are involved in cytoskeletal organization and the coagulation cascade that contributes to platelet activation, release of granule contents, and aggregation, which culminate in thrombus formation. These results have important implications in our understanding of the molecular mechanisms associated with the development of HTN, and in consequence, the development of new strategies to counteract the cardiovascular disorders associated with constitutive activation of platelets in HTN.

Proteomics: A Tool to Study Platelet Function

Platelets are components of the blood that are highly reactive, and they quickly respond to multiple physiological and pathophysiological processes. In the last decade, it became clear that platelets are the key components of circulation, linking hemostasis, innate, and acquired immunity. Protein composition, localization, and activity are crucial for platelet function and regulation. The current state of mass spectrometry-based proteomics has tremendous potential to identify and quantify thousands of proteins from a minimal amount of material, unravel multiple post-translational modifications, and monitor platelet activity during drug treatments. This review focuses on the role of proteomics in understanding the molecular basics of the classical and newly emerging functions of platelets. including the recently described role of platelets in immunology and the development of COVID-19.The state-of-the-art proteomic technologies and their application in studying platelet biogenesis, signaling, and storage are described, and the potential of newly appeared trapped ion mobility spectrometry (TIMS) is highlighted. Additionally, implementing proteomic methods in platelet transfusion medicine, and as a diagnostic and prognostic tool, is discussed.

Platelets in Healthy and Disease States: From Biomarkers Discovery to Drug Targets Identification by Proteomics

Platelets are a heterogeneous small anucleate blood cell population with a central role both in physiological haemostasis and in pathological states, spanning from thrombosis to inflammation, and cancer. Recent advances in proteomic studies provided additional important information concerning the platelet biology and the response of platelets to several pathophysiological pathways. Platelets circulate systemically and can be easily isolated from human samples, making proteomic application very interesting for characterizing the complexity of platelet functions in health and disease as well as for identifying and quantifying potential platelet proteins as biomarkers and novel antiplatelet therapeutic targets. To date, the highly dynamic protein content of platelets has been studied in resting and activated platelets, and several subproteomes have been characterized including platelet-derived microparticles, platelet granules, platelet releasates, platelet membrane proteins, and specific platelet post-translational modifications. In this review, a critical overview is provided on principal platelet proteomic studies focused on platelet biology from signaling to granules content, platelet proteome changes in several diseases, and the impact of drugs on platelet functions. Moreover, recent advances in quantitative platelet proteomics are discussed, emphasizing the importance of targeted quantification methods for more precise, robust and accurate quantification of selected proteins, which might be used as biomarkers for disease diagnosis, prognosis and therapy, and their strong clinical impact in the near future.

Erythrocyte and platelet proteomics in hematological disorders

Erythrocytes undergo ineffective erythropoesis, hemolysis, and premature eryptosis in sickle cell disease and thalassemia. Abnormal hemoglobin variants associated with hemoglobinopathy lead to vesiculation, membrane instability, and loss of membrane asymmetry with exposal of phosphatidylserine. This potentiates thrombin generation resulting in activation of the coagulation cascade responsible for subclinical phenotypes. Platelet activation also results in the release of microparticles, which express and transfer functional receptors from platelet membrane, playing key roles in vascular reactivity and activation of intracellular signaling pathways. Over the last decade, proteomics had proven to be an important field of research in studies of blood and blood diseases. Blood cells and its fluidic components have been proven to be easy systems for studying differential expressions of proteins in hematological diseases encompassing hemoglobinopathies, different types of anemias, myeloproliferative disorders, and coagulopathies. Proteomic studies of erythrocytes and platelets reported from several groups have highlighted various factors that intersect the signaling networks in these anucleate systems. In this review, we have elaborated on the current scenario of anucleate blood cell proteomes in normal and diseased individuals and the cross-talk between the two major constituent cell types of circulating blood.

Platelet proteomics: state of the art and future perspective

Platelets pose unique challenges to cell biologists due to their lack of nucleus and low levels of messenger RNA. Platelets cannot be cultured in great abundance or manipulated using common recombinant DNA technologies. As a result, platelet research has lagged behind that of nucleated cells. The advent of mass spectrometry and its application to protein biochemistry brought with it great hopes for the platelet community that are now being realized. This technology is ideally suited for identifying low-abundance proteins, protein-protein interactions, and post-translational modifications in complex protein mixtures. Over the past 10 years, proteomics has delivered in many ways, providing platelet biologists with a comprehensive list of proteins expressed in platelets, information on post-translational modifications, protein interactions and sub-cellular localization. Several novel and important platelet membrane proteins, including CLEC-2, CD148, G6b-B, G6f, and Hsp47, have been identified using proteomics-based approaches. New, more sensitive instrumentation and novel approaches are making it increasingly possible to identify ever lower amounts of proteins. In this chapter we highlight some of the major achievements of platelet proteomics to date, discussing challenges and how they were overcome. We also discuss new frontiers and applications of proteomics to platelets and microparticles in health and disease, as we strive to better understand the molecular mechanisms underlying the platelet response to vascular injury.

Proteomics of proteins associated with astaxanthin accumulation in the green algae Haematococcus lacustris under the influence of sodium orthovanadate

An extensive proteomics analysis has identified proteins associated with astaxanthin accumulation in the green algae Haematococcus lacustris under oxidative stress induced by sodium orthovanadate (SOV). Measurement of total carotenoid accumulation per cell biomass showed an increase from 81 to 136 pg/cell after being exposed to 2.5 mM SOV, when compared to the control cells at day 3 of cultivation. A total of 83 proteins were differentially expressed in SOV-treated H. lacustris in comparison with control cells. They consisted of 34 down-regulated and 49 up-regulated proteins. Of these, 17 highly-expressed proteins were analyzed by MALDI-TOF-MS to identify the function of the differentially expressed proteins in response to oxidative stress in H. lacustris.

The value of proteomics for the diagnosis of a platelet-related bleeding disorder

Familial bleeding problems are frequently difficult to diagnose because currently used clinical tests cannot identify intracellular molecular defects of platelets. Using platelet proteomics, a comprehensive analytical tool, we diagnosed a family with severe bleeding problems of unknown origin with Quebec Platelet Disorder. Prior to proteomic analysis, we determined platelet counts, presence of glycoprotein (GP) Ib and GPIIb/IIIa, platelet aggregation, dense granule content and release, plasma levels of fibrinogen, Factor XIII and fibrin degradation products in four family members. Abnormalities were detected in platelet aggregation studies, which revealed variably reduced responses to ADP, collagen and epinephrine with concomitantly decreased ATP/serotonin secretion. In addition, D-dimer levels were significantly elevated 72 hours after in vitro thrombin stimulation of platelet-rich plasma. Together with the autosomal dominant inheritance and the delayed onset of bleeding in two of the four patients these results did not support any known platelet disorder. Therefore, the proteome of platelet lysates separated by one-dimensional SDS-PAGE was analysed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Platelet proteomics showed reduced amounts of alpha-granule proteins multimerin, fibrinogen and thrombospondin-1 in patient compared to control samples suggestive of Quebec Platelet Disorder. The diagnosis of Quebec Platelet Disorder was confirmed by urokinase-specific Western blots. Urokinase causes the degradation of alpha-granule proteins in this disorder. Diagnosis of rare bleeding disorders has important implications for prophylactic and acute treatment of bleeding patients. This is the first report using proteomics to identify a familial platelet defect.

Proteomic Biomarkers of Atherosclerosis

SUMMARY: Biomarkers provide a powerful approach to understanding the spectrum of cardiovascular diseases. They have application in screening, diagnostic, prognostication, prediction of recurrences and monitoring of therapy. The "omics" tool are becoming very useful in the development of new biomarkers in cardiovascular diseases. Among them, proteomics is especially fitted to look for new proteins in health and disease and is playing a significant role in the development of new diagnostic tools in cardiovascular diagnosis and prognosis. This review provides an overview of progress in applying proteomics to atherosclerosis. First, we describe novel proteins identified analysing atherosclerotic plaques directly. Careful analysis of proteins within the atherosclerotic vascular tissue can provide a repertoire of proteins involved in vascular remodelling and atherogenesis. Second, we discuss recent data concerning proteins secreted by atherosclerotic plaques. The definition of the atheroma plaque secretome resides in that proteins secreted by arteries can be very good candidates of novel biomarkers. Finally we describe proteins that have been differentially expressed (versus controls) by individual cells which constitute atheroma plaques (endothelial cells, vascular smooth muscle cells, macrophages and foam cells) as well as by circulating cells (monocytes, platelets) or novel biomarkers present in plasma.

A small heat shock protein of Ostertagia ostertagi: stage-specific expression, heat inducibility, and protection trial

In this study, we isolated and analyzed a small heat shock protein (HSP) of Ostertagia ostertagi (Oo-HSP18). Oo-hsp18 is encoded by a single-copy gene and the full-length cDNA represents an 18-kDa protein. The expression of Oo-hsp18 is highly stage specific and restricted to the adult stage. The protein is synthesized in a tissue-specific manner and localized in the body muscle layer. The levels of Oo-hsp18 mRNAs are sharply induced by heat shock but not by other stressors such as levamisole and H2O2. A vaccination trial with recombinant Oo-HSP18 failed to protect calves against a challenge infection.

Serum protein profiling in patients with inflammatory bowel diseases using selective solid-phase bulk extraction, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and chemometric data analysis

The identification of new biomarkers or a disease-related protein fingerprint for inflammatory bowel diseases (IBDs) represents a major task in the diagnosis, prognosis and pharmacological therapy. To address these issues, a simple and rapid analytical proteomic method for serum protein profiling based on selective beads-based solid-phase bulk extraction, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and chemometric data analysis was developed. Serum proteins from healthy subjects (22) and patients with Crohn's disease (15) and ulcerative colitis (26) were selectively extracted according to reversed-phase (C18), strong anion-exchange (SAX) and metal ion affinity (IDA-Cu(II)) principles. This approach allowed enrichment of serum proteins/peptides due to the high interaction surface between analytes and the solid phase and high recovery due to the elution step performed directly on the MALDI-target plate. The MALDI-TOF MS serum protein profiles were acquired and, after a data pre-processing step, analyzed by linear discriminant analysis (LDA), a chemometric classification technique, in order to classify serum samples among healthy subjects and patients with inflammatory bowel diseases (IBDs). Since the high number of variables in the MALDI spectra (more than 16000 m/z values) prevents the use of LDA, the variables were reduced to 10-20 by features selection, thus allowing the evaluation of a pattern of m/z values with high discriminant power. Serum protein profiles obtained by reversed-phase extraction and the selection of 20 m/z values gave the best overall prediction ability (96.9%). The recognition of these m/z values may allow the identification of protein biomarkers involved in IBDs.

Expression of the recombinant protein disulphide isomerase of Teladorsagia circumcincta

The aim of this experiment was to find an antigen from Teladorsagia circumcincta to measure the level of IgA in ovine serum samples. Previous experiments used the titre of IgA to select sheep resistant to infection with T. circumcincta. By Western blotting 22 experimentally infected ewes recognized many proteins, but not all of them were recognized by all animals. Sheep were divided into two groups of animals: those that recognized a protein in Western blotting and those that did not. Among all proteins, three showed significant associations between protein recognition and the titre of IgA in the serum.

Proteomic approaches to dissect platelet function: Half the story

Platelets play critical roles in diverse hemostatic and pathologic disorders and are broadly implicated in various biological processes that include inflammation, wound healing, and thrombosis. Recent progress in high-throughput mRNA and protein profiling techniques has advanced our understanding of the biological functions of platelets. Platelet proteomics has been adopted to decode the complex processes that underlie platelet function by identifying novel platelet-expressed proteins, dissecting mechanisms of signal or metabolic pathways, and analyzing functional changes of the platelet proteome in normal and pathologic states. The integration of transcriptomics and proteomics, coupled with progress in bioinformatics, provides novel tools for dissecting platelet biology. In this review, we focus on current advances in platelet proteomic studies, with emphasis on the importance of parallel transcriptomic studies to optimally dissect platelet function. Applications of these global profiling approaches to investigate platelet genetic diseases and platelet-related disorders are also addressed.

Miniaturized Solid-Phase Extraction and Sample Preparation for MALDI MS Using a Microfabricated Integrated Selective Enrichment Target

A microfabricated proteomic sample preparation and sample presentation device, Integrated Selective Enrichment Target, (ISET), comprising an array of 96 perforated nanovials is described. Each perforated nanovial can be filled with solid-phase extraction media for purification and concentration of peptides prior to matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS). The validity of the ISET sample preparation is shown by analysis of low nM-pM standard samples, as well as biological samples. The ISET solid-phase extraction sample preparation was compared to ZipTip and MassPREP PROtarget sample preparation, demonstrating a superior performance with respect to number of detected peptides and signal intensity of detected peptides.

Proteome analysis of signaling cascades in human platelets

During the last 15 years, advances in mass spectrometry (MS) instrumentation and techniques have revolutionized the emerging field of proteomics. Proteomics technology allows a comprehensive and efficient analysis of the protein content (i.e., the proteome) of any cell, tissue or biological fluid and has become an indispensable tool in biomedical research, complementing the powerful field of genomics. Proteomics is based on the huge analytical power offered by mass spectrometry in combination with several separation techniques, such as two-dimensional gel electrophoresis (2-DE) or multidimensional liquid chromatography. The technology is particularly suitable for platelets because of the absence of a nucleus. In the recent years, there has been success in mapping the proteome of the platelet in a basal state. Furthermore, a handful of research groups have also applied this technology to the study of signaling cascades in human platelets, allowing the identification of novel platelet signaling proteins and phosphorylation events. Those studies provide new insights into the mechanisms of platelet activation and build the basis for the development of therapeutic agents for thrombotic disease. This article focus on the application of 2-DE-based proteomics to the study of signaling cascades in human platelets.

Platelet genomics and proteomics in human health and disease

Proteomic and genomic technologies provide powerful tools for characterizing the multitude of events that occur in the anucleate platelet. These technologies are beginning to define the complete platelet transcriptome and proteome as well as the protein-protein interactions critical for platelet function. The integration of these results provides the opportunity to identify those proteins involved in discrete facets of platelet function. Here we summarize the findings of platelet proteome and transcriptome studies and their application to diseases of platelet function.

Applying proteomics technology to platelet research

Platelets are small enucleated cells that circulate in the blood, where they play a key role in hemostasis and contribute to the formation of vascular plugs. Pathologically, they are involved in thrombosis and heart disease. Because platelets do not have a nucleus, proteomics offers a powerful way to approach their biology. Proteomics technology is based on the huge analytical power offered by mass spectrometry in combination with several separation techniques, such as two-dimensional gel electrophoresis (2DGE) or multidimensional liquid chromatography. Proteomics provides information about the complete set of proteins present in platelets, the platelet proteome, including post-translational variants. Over the last years, several research groups have applied proteomics to platelet research. A detailed analysis of the general proteome and signaling cascades in human platelets will improve our knowledge of platelet function, and thereby aid the development of new therapeutic agents to treat thrombotic diseases. This review presents the major advances in mass spectrometry-based proteomics techniques and their application to platelet research, and analyzes in detail the most relevant contributions to the field.

Two-dimensional Blue Native/sodium dodecyl sulfate gel electrophoresis for analysis of multimeric proteins in platelets

Two-dimensional (2-D) Blue Native/SDS gel electrophoresis combines a first-dimensional separation of monomeric and multimeric proteins in their native state with a second denaturing dimension. These high-resolution 2-D gels aim at identifying multiprotein complexes with respect to their subunit composition. We applied this method for the first time to analyze two human platelet subproteomes: the cytosolic and the microsomal membrane protein fraction. Solubilization of platelet membrane proteins was achieved with the nondenaturing detergent n-dodecyl-beta-D-maltoside. To validate native solubilization conditions, we demonstrated the correct assembly of the Na,K-ATPase, a functional multimeric transmembrane protein, when expressed in Xenopus oocytes. We identified 63 platelet proteins after in-gel tryptic digestion of 58 selected protein spots and liquid chromatography-coupled tandem mass spectrometry. Nine proteins were detected for the first time in platelets by a proteomic approach. We also show that this technology efficiently resolves several known membrane and cytosolic multiprotein complexes. Blue Native/SDS gel electrophoresis is thus a valuable procedure to analyze specific platelet subproteomes, like the membrane(-bound) protein fraction, by mass spectrometry and immunoblotting and could be relevant for the study of protein-protein interactions generated following platelet activation.

An aspartyl protease inhibitor of Ostertagia ostertagi: Molecular cloning, analysis of stage and tissue specific expression and vaccine trial

Protease inhibitors are thought to protect intestinal parasitic nematodes from their hostile proteolytic environment. In a previous study, screening of Ostertagia ostertagi cDNA libraries with local antibody probes of the abomasal lymph nodes and mucus revealed a (28 kDa) aspartyl protease inhibitor (API), which was exclusively recognised by antibodies from immune calves. Here we report the molecular characterization of Oo-API (sequence analysis, developmental expression and localization) and a vaccine trial in cattle with the native and recombinant baculo-expressed antigen. The full-length open reading frame of api encodes a protein of 28 kDa. The sequence showed 82% significant homology to an Aspin homologue from Trichostrongylus colubriformis (AA034715). The cDNA encoding the full-length sequence was cloned in a bacterial pET expression vector and the pVec 35 baculovirus vector. Polyclonal rabbit serum against the Escherichia coli-expressed protein was used to develop Western Blots of extracts and ES and to localize the antigen on L3, L4 and adult worm sections. The protein was expressed in all life stages, which was confirmed by real-time polymerase chain reaction (RT-PCR), and was mainly localized in the cuticle of L3, the intestinal cells of L4, and the gut and sphincter of adult worms. Polyclonal serum was also used to affinity purify the native protein. Vaccination of calves with native Oo-API and baculovirus-expressed Oo-rbAPI in combination with QuilA resulted in no protection against Ostertagia challenge infections.

Molecular analysis of astacin-like metalloproteases of Ostertagia ostertagi

In this study, we describe the molecular analysis of zinc-metalloproteases from the abomasal nematode Ostertagia ostertagi which were exclusively recognized by local antibodies of immune cattle. Full-length or partial coding sequences of 4 different zinc-metalloprotease cDNAs of Ostertagia (met-1, -2, -3 and -4) were amplified using gene-specific primers using the 3'- and 5'-Rapid Amplification of cDNA Ends (RACE) technique. Sequence analysis identified the cDNAs as encoding zinc-metalloproteases, which showed between 62% and 70% homology to a metalloprotease 1 precursor of Ancylostoma caninum. The full-length cDNA of met-1 consists of an open reading frame (ORF) of 586 amino acids which contains 5 potential N-glycosylation sites and a predicted zinc-binding domain (HEBXHXBGFXHEXXRXDRD). The complete coding sequence of met-3 contains an ORF of 508 aa and the same conserved zinc-binding domain. These domains are signature sequences of the astacin family of the superfamily of metzincin metalloproteases. The presence of a threonine amino acid after the third histidine in MET-1 and MET-3, however, may place them in a new family or subfamily. Real-time PCR analysis of L3, exsheathed L3, L4 and adult cDNA identified transcription of the 4 metalloproteases in different life-stages. The protein MET-1 was expressed in insect cells using the baculovirus expression system but the immunization of calves with this molecule did not lead to protection against challenge infection.

Large-scale identification of tubulin-binding proteins provides insight on subcellular trafficking, metabolic channeling, and signaling in plant cells

Microtubules play an essential role in the growth and development of plants and are known to be involved in regulating many cellular processes ranging from translation to signaling. In this article, we describe the proteomic characterization of Arabidopsis tubulin-binding proteins that were purified using tubulin affinity chromatography. Microtubule co-sedimentation assays indicated that most, if not all, of the proteins in the tubulin-binding protein fraction possessed microtubule-binding activity. Two-dimensional gel electrophoresis of the tubulin-binding protein fraction was performed, and 86 protein spots were excised and analyzed for protein identification. A total of 122 proteins were identified with high confidence using LC-MS/MS. These proteins were grouped into six categories based on their predicted functions: microtubule-associated proteins, translation factors, RNA-binding proteins, signaling proteins, metabolic enzymes, and proteins with other functions. Almost one-half of the proteins identified in this fraction were related to proteins that have previously been reported to interact with microtubules. This study represents the first large-scale proteomic identification of eukaryotic cytoskeleton-binding proteins, and provides insight on subcellular trafficking, metabolic channeling, and signaling in plant cells.

Platelet proteomics

As anucleate cell particles, platelets do not lend themselves to analysis by traditional cell and molecular biology techniques. Moreover, while valuable information may be gleaned from studies of messenger RNA in platelets, the rapid events in platelets are not governed by or dependent on alterations in gene expression. In contrast, proteomics, the study of the protein complement of a genome, will have a major impact on platelet biology. It offers the opportunity to comprehensively describe the proteins involved in discrete elements of platelet function, from the subsecond events following platelet activation and adhesion through to platelet aggregation and granule secretion. As the function of every protein is understood and as the mechanisms that regulate protein modifications are unravelled, we will discover a wealth of proteins that are themselves potential therapeutic agents or novel targets for the development of diagnostics and drugs. Here we review the current applications of proteomics to platelet research. We briefly describe various proteomic approaches to unravel platelet biology, including the documentation of platelet proteins, the investigation of thrombin-activated phosphotyrosine signaling networks and the analysis of the proteins that are secreted upon platelet activation. Proteomics is a young field and there are only a handful of published examples applying proteomics to platelet research. This number will increase over the next few years, as advances in analytical methods allow a more functional analysis of the platelet proteome.

Identification of the phosphotyrosine proteome from thrombin activated platelets

Signalling cascades are regulated both positively and negatively by tyrosine phosphorylation. Integrin mediated platelet adhesion triggers signal transduction cascades involving translocation of proteins and tyrosine phosphorylation events, ultimately causing large signalling complexes to be assembled. In resting platelets, a small number of phosphorylated proteins are evident with molecular mass of 50-62 kDa and 120-130 kDa. In thrombin activated human platelets, however, there is a large increase in the number of tyrosine phosphorylated signalling proteins detected. These proteins include pCas (130 kDa), FAK (125 kDa), PI(3)k (85 kDa) and src (85 kDa). However, it is unlikely that this list of proteins represents all the dynamic changes that occur after platelet activation and it is understood that more proteins remain unidentified. In this study, we propose a method for the isolation of the phosphotyrosine proteome from both resting and thrombin activated human platelets. All the dynamic phosphotyrosine events that occur in the platelet after thrombin activation were isolated by immunoprecipitation, using the monoclonal antibody 4G10, allowing us to obtain higher concentrations of relatively low abundant proteins. The resulting phosphotyrosine proteomes were separated by two-dimensional gel electrophoresis. Sixty-seven proteins were reproducibly found to be unique in the thrombin activated platelet proteome when compared to resting platelets. We have positively identified ten of these proteins by Western blotting and matrix-assisted laser desorption/ionisation-time of flight mass spectrometry and these include FAK, Syk, ALK-4, P2X6 and MAPK kinase kinase. This proteomics approach to understanding the signalling events following platelet activation may elucidate potential drug targets for the treatment of coronary thrombosis.

Conventional and functional proteomics using large format two-dimensional gel electrophoresis 24 hours after controlled cortical impact in postnatal day 17 rats

Conventional and functional proteomics have significant potential to expand our understanding of traumatic brain injury (TBI) but have not yet been used. The purpose of the present study was to examine global hippocampal protein changes in postnatal day (PND) 17 immature rats 24 h after moderate controlled cortical impact (CCI). Silver nitrate stains or protein kinase B (PKB) phosphoprotein substrate antibodies were used to evaluate high abundance or PKB pathway signal transduction proteins representing conventional and functional proteomic approaches, respectively. Isoelectric focusing was performed over a nonlinear pH range of 3-10 with immobilized pH gradients (IPG strips) using supernatant from the most soluble cellular protein fraction of hippocampal tissue protein lysates from six paired sham and injured PND 17 rats. Approximately 1,500 proteins were found in each silver stained gel with 40% matching of proteins. Of these 600 proteins, 52% showed a twofold, 20% a fivefold, and 10% a 10-fold decrease or increase. Spot matching with existing protein databases revealed changes in important cytoskeletal and cell signalling proteins. PKB substrate protein phosphorylation was best seen in large format two-dimensional blots and known substrates of PKB such as glucose transporter proteins 3 and 4 and forkhead transcription factors, identified based upon molecular mass and charge, showed altered phosphorylation 24 h after injury. These results suggest that combined conventional and functional proteomic approaches are powerful, complementary and synergistic tools revealing multiple protein changes and posttranslational protein modifications that allow for more specific and comprehensive functional assessments after pediatric TBI.

The postgenomic age: characterization of proteomes

Global analysis of biological systems is becoming increasingly feasible as technologies that facilitate genome-wide analyses of gene expression are developed. Proteomics is the global analysis of expressed proteins (including posttranslational modifications) and seeks to establish the relationship between genome sequence, expressed proteins, protein-protein interactions, and cell and tissue phenotype. While the relative abundance of transcripts can be quantified using gene expression microarrays, the identification and quantitation of expressed proteins is more challenging. Nevertheless, the potential payoff for global protein analyses is immense because identification of distinctive protein signatures associated with cell function may provide novel therapeutic targets, molecular markers of disease, and increased understanding of determinants of cell phenotype. The challenges and promises of applications of established and emerging proteome strategies to detect and quantify differentially expressed proteins in culture cells are discussed.

Current literature in mass spectrometry

In order to keep subscribers up-to-date with the latest developments in their field, John Wiley & Sons are providing a current awareness service in each issue of the journal. The bibliography contains newly published material in the field of mass spectrometry. Each bibliography is divided into 11 sections: 1 Books, Reviews & Symposia; 2 Instrumental Techniques & Methods; 3 Gas Phase Ion Chemistry; 4 Biology/Biochemistry: Amino Acids, Peptides & Proteins; Carbohydrates; Lipids; Nucleic Acids; 5 Pharmacology/Toxicology; 6 Natural Products; 7 Analysis of Organic Compounds; 8 Analysis of Inorganics/Organometallics; 9 Surface Analysis; 10 Environmental Analysis; 11 Elemental Analysis. Within each section, articles are listed in alphabetical order with respect to author (3 Weeks journals - Search completed at 28th. June 2000)