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Results for “post translational modification”

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PubMed1986

Barium modulates c-fos expression and post-translational modification.

The addition of exogenous barium ions to PC12 rat pheochromocytoma cells elicits a transient induction of the c-fos gene. Induction is antagonized by extracellular calcium and the dihydropyridine calcium channel blockers, and it is attenuated in the presence of calmodulin inhibitors. Thus, barium appears to enter the cell through a voltage-dependent calcium channel and, either directly or indirectly, interacts with calmodulin to stimulate c-fos expression. This property of barium is not shared by a range of di- and trivalent cations examined. Agents that induce the c-fos gene in PC12 cells may be divided into two broad categories. The first comprises polypeptide growth factors and phorbol esters, which give rise to a c-fos protein that undergoes extensive post-translational modification. The second, which comprises depolarizing agents and barium ions, acts via calcium channels and yields a c-fos protein that undergoes less extensive post-translational modification. These different forms of c-fos protein can be distinguished on the basis of their apparent molecular weights on sodium dodecyl sulfate/polyacrylamide gels.

Barium↗

PubMed2004

Poly(ADP-ribosyl)ation as a DNA damage-induced post-translational modification regulating poly(ADP-ribose) polymerase-1-topoisomerase I interaction.

Poly(ADP-ribosyl)ation is a post-translational modification that occurs immediately after exposure of cells to DNA damaging agents. In vivo, 90% of ADP-ribose polymers are attached to the automodification domain of poly(ADP-ribose) polymerase-1 (PARP-1), the main enzyme catalyzing this modification reaction. This enzyme forms complexes with transcription initiation, DNA replication, and DNA repair factors. In most known cases, the interactions occur through the automodification domain. However, functional implications of the automodification reaction on these interactions have not yet been elucidated. In the present study, we created fluorescent protein-tagged PARP-1 to study this enzyme in live cells and focused on the interaction between PARP-1 and topoisomerase I (Topo I), one of the enzymes that interacts with PARP-1 in vitro. Here, we demonstrate that PARP-1 co-localizes with Topo I throughout the cell cycle. Results from bioluminescence resonance energy transfer assays suggest that the co-localization is because of a direct protein-protein interaction. In response to DNA damage, PARP-1 de-localization and a reduction in bioluminescence resonance energy transfer signal because of the automodification reaction are observed, suggesting that the automodification reaction results in the disruption of the interaction between PARP-1 and Topo I. Because Topo I activity has been reported to be promoted by PARP-1, we then investigated the effect of the disruption of this interaction on Topo I activity, and we found that this disruption results in the reduction of Topo I activity. These results suggest that a function for the automodification reaction is to regulate the interaction between PARP-1 and Topo I, and consequently, the Topo I activity, in response to DNA damage.

Animals↗

PubMed2002

A novel in vivo post-translational modification of p53 by PARP-1 in MPTP-induced parkinsonism.

Sporadic Parkinson's disease (PD) affects primarily dopaminergic neurons of the substantia nigra pars compacta. There is evidence of necrotic and apoptotic neuronal death in PD, but the mechanisms behind selected dopaminergic neuronal death remain unknown. The tumor suppressor protein p53 functions to selectively destroy stressed or abnormal cells during life and development by means of necrosis and apoptosis. Activation of p53 leads to death in a variety of cells including neurons. p53 is a target of the nuclear enzyme Poly(ADP-ribose)polymerase (PARP), and PARP is activated following DNA damage that occurs following 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurotoxicity. MPTP is the favored in vivo model of PD, and reproduces the pathophysiology, anatomy and biochemistry of PD. p53 protein normally exhibits a fleeting half-life, and regulation of p53 stability and activation is achieved mainly by post-translational modification. We find that p53 is heavily poly(ADP-ribosyl)ated by PARP-1 following MPTP intoxication. This post-translational modification serves to stabilize p53 and alters its transactivation of downstream genes. These influences of PARP-1 on p53 may underlie the mechanisms of MPTP-induced parkinsonism and other models of neuronal death.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗

PubMed2001

Post-translational modifications of heterologously expressed cholecystokinin in Saccharomyces cerevisiae.

The vertebrate neuroendocrine peptide cholecystokinin (CCK) is subjected to numerous post-translational modifications upon maturation to bioactive CCK. However, the current knowledge of the proteolytic processing of proCCK, as reviewed here, is not complete. We have chosen Saccharomyces cerevisiae as a model to study these endoproteolytic processing events. Expression of proCCK as a fusion protein to the prepro leader peptide of alpha-mating factor directed the protein through the secretory pathway and resulted in nanomolar concentrations of secreted glycine-extended CCK. The CCK peptides showed many correlations to the known endoproteolytic processing products of proCCK in endocrine cells. Especially the processing to the abundant form, CCK-22, was investigated and it is suggested that a novel enzyme is responsible for its production. Thus, yeast may be used to study the proteolysis of proCCK with the aim to identify mammalian homologues involved in maturation of CCK.

Amino Acid Sequence↗

PubMed1988

Tubulin post-translational modifications and the construction of microtubular organelles in Trypanosoma brucei.

We have used specific monoclonal antibodies to facilitate a study of acetylated and tyrosinated alpha-tubulin in the microtubule (MT) arrays in the Trypanosoma brucei cell. Acetylated alpha-tubulin is not solely located in the stable microtubular arrays but is present even in the ephemeral microtubules of the mitotic spindle. Moreover, there is a uniform distribution of this isoform in all arrays. Studies of flagella complexes show that acetylation is concomitant with assembly of MTs. There is no subsequent major modulation in the content of acetylated alpha-tubulin in MTs. Conversely, polymerizing flagellar MTs have a high tyrosinated alpha-tubulin content, which is subsequently reduced to a basal level at a discrete point in the cell cycle. The MTs of the intranuclear mitotic spindle appear never to contain tyrosinated alpha-tubulin, suggesting that they are actually constructed of detyrosinated alpha-tubulin or that detyrosination is extremely rapid at this time in the cell cycle. T. brucei therefore, represents a cell type with extremely active mechanisms for the post-translational modification of alpha-tubulin. Our analyses of the timing of acquisition and modulation in relation to MT construction in T. brucei, suggest that acetylation and detyrosination of alpha-tubulin are two independently regulated post-translational modifications, that are not uniquely associated with particular subsets of MTs of defined lability, position or function. Post-assembly detyrosination of alpha-tubulin may provide a mechanism whereby the cell could discriminate between new and old MTs, during construction of the cytoskeleton through the cell cycle. However, we also suggest that continuation of detyrosination, allows the cell, at cell division, to partition into daughter cells two equivalent sets of cytoskeletal MTs.

Acetylation↗

PubMed2002

Post-translational modifications in prion proteins.

Prions are a novel class of infectious pathogens that cause a group of fatal prion diseases in which the benign cellular form of the prion protein (PrP(C)) is transformed into the disease-related scrapie variant (PrP(SC)). The two PrP isoforms differ in their structure and resistance to degradation. The molecular mechanism by which the PrP(SC) is formed and causes infectivity or neurodegeneration is not known. In a compelling and emerging view, post-translational modifications (or the lack thereof) play roles in the transformation of PrP(C) to PrP(SC). Human PrP contains two consensus sites for N-linked glycosylation, at Asn181 and Asn197. From the functional standpoint, glycosylation can modify either the conformation of PrP(C), or the stability of PrP(SC) and, hence, the rate of PrP(SC) clearance. So far the NMR structures of only recombinant, non-glycosylated prions are known, while the structure of the glycosylated form is estimated by molecular modeling. A number of native amino acid mutations in PrP can be mapped near the glycosylation sites. Normal prion protein has been demonstrated to be a copper binding protein, and increasing evidence has shown correlation between the level of PrP expression and tolerance to oxidative stress. Moreover, histochemistry for nitrotyrosine is used for detection of neuronal labeling, a sign of a peroxynitrite-mediated neuronal degradation and a marker for nitrative stress in scrapie-infected mouse brains. It is an intriguing proposition that the post-translational modifications alone, or in combination with amino acid changes, play dominant roles in the pathogenic transformation of PrP(C) to PrP(SC).

Amino Acid Substitution↗

PubMed1992

Post-translational modifications of Drosophila acetylcholinesterase. In vitro mutagenesis and expression in Xenopus oocytes.

Drosophila acetylcholinesterase (EC 3.1.1.7) is a 150-kDa glycoprotein anchored in plasmic membranes via a glycolipid. It is composed of two active subunits which are themselves made of two noncovalently linked polypeptides of 18 and 55 kDa resulting from the proteolysis of a single precursor of 75 kDa. Active Drosophila acetylcholinesterase can be expressed in Xenopus oocytes as an excreted protein. We have identified some of the amino acids essential in post-translational modifications of the protein by site-directed mutagenesis and expression of mutants in this system. The intersubunit disulfide bond involves cysteine at position 615. Cleavage of the 75-kDa precursor, as observed in Drosophila, originates from a hydrophilic peptide (in position 148 to 180) which does not exist in cholinesterase sequences from vertebrates. This cleavage is associated with excretion out of the cell. Drosophila acetylcholinesterase exhibits four effective sites of asparagine-linked glycosylation in positions 126, 174, 331, and 531. We show that glycosylations and dimerization protect the protein against proteolytic digestion. In contrast, none of these post-translational modifications significantly affects the activity of acetylcholinesterase or affinity for its substrate.

Acetylcholinesterase↗

PubMed2006

ModifiComb, a new proteomic tool for mapping substoichiometric post-translational modifications, finding novel types of modifications, and fingerprinting complex protein mixtures.

A major challenge in proteomics is to fully identify and characterize the post-translational modification (PTM) patterns present at any given time in cells, tissues, and organisms. Here we present a fast and reliable method ("ModifiComb") for mapping hundreds types of PTMs at a time, including novel and unexpected PTMs. The high mass accuracy of Fourier transform mass spectrometry provides in many cases unique elemental composition of the PTM through the difference DeltaM between the molecular masses of the modified and unmodified peptides, whereas the retention time difference DeltaRT between their elution in reversed-phase liquid chromatography provides an additional dimension for PTM identification. Abundant sequence information obtained with complementary fragmentation techniques using ion-neutral collisions and electron capture often locates the modification to a single residue. The (DeltaM, DeltaRT) maps are representative of the proteome and its overall modification state and may be used for database-independent organism identification, comparative proteomic studies, and biomarker discovery. Examples of newly found modifications include +12.000 Da (+C atom) incorporation into proline residues of peptides from proline-rich proteins found in human saliva. This modification is hypothesized to increase the known activity of the peptide.

Adult↗

PubMed2004

Identification of altered protein expression and post-translational modifications in primary colorectal cancer by using agarose two-dimensional gel electrophoresis.

PURPOSE: Although numerous proteome studies have been performed recently to identify cancer-related changes in protein expression, only a limited display of relatively abundant proteins has been identified. The aim of this study is to identify novel proteins as potential tumor markers in primary colorectal cancer tissues using a high-resolution two-dimensional gel electrophoresis (2-DE). EXPERIMENTAL DESIGN: 2-DE using an agarose gel for isoelectric focusing was used to compare protein profiling of 10 colorectal cancer tissues and adjacent normal mucosa. Altered expression and post-translational modification of several proteins were examined using Western blot analysis and immunohistochemistry. RESULTS: Ninety-seven proteins of 107 spots (90.7%) that were differentially expressed between matched normal and tumor tissues were identified by mass spectrometry. Among them, 42 unique proteins (49 spots) significantly increased or decreased in the tumors. They include eukaryotic translation initiation factor 4H, inorganic pyrophosphatase, anterior gradient 2 homologue, aldolase A, and chloride intracellular channel 1, whose elevated expression in tumor tissues was confirmed by Western blot analysis and immunohistochemistry. Interestingly, only isoform 1 of two transcript variants of eukaryotic translation initiation factor 4H was greatly up-regulated in most of the tumor tissues. Moreover, post-translational modifications of the prolyl-4-hydroxylase beta subunit and annexin A2 also were identified. CONCLUSIONS: We identified several novel proteins with altered expression in primary colorectal cancer using agarose 2-DE. This method is a powerful technique with which to search for not only quantitative but also qualitative changes in a biological process of interest and may contribute to the deeper understanding of underlying mechanisms of human cancer.

Aged↗

PubMed2005

The absolute quantification strategy: a general procedure for the quantification of proteins and post-translational modifications.

Advances in biological mass spectrometry have resulted in the development of numerous strategies for the large-scale quantification of protein expression levels within cells. These measurements of protein expression are most commonly accomplished through differential incorporation of stable isotopes into cellular proteins. Several variations of the stable isotope quantification method have been demonstrated, differing in isotope composition and incorporation strategy. In general, the majority of these methods establish only relative quantification of expressed proteins. To address this, the absolute quantification (AQUA) strategy was developed for the precise determination of protein expression and post-translational modification levels. The AQUA method relies on the use of a synthetic internal standard peptide that is introduced at a known concentration to cell lysates during digestion. This AQUA peptide precisely mimics a peptide produced during proteolysis of the target protein, except that it is enriched in certain stable isotopes. Analysis of the proteolyzed sample by a selected reaction monitoring (SRM) experiment in a tandem mass spectrometer results in the direct detection and quantification of both the native peptide and isotope labeled AQUA internal standard peptide. As an example, the development and application of a method to measure a tryptic peptide representing the amount of polyubiquitin chain formation through lysine 48 (K48) is presented. The simplicity and sensitivity of the method, coupled with the widespread availability of tandem mass spectrometers, make the AQUA strategy a highly useful procedure for measuring the levels of proteins and post-translational modifications directly from cell lysates.

Animals↗

PubMed1998

Co- and/or post-translational modifications are critical for TCH4 XET activity.

TCH4 encodes a xyloglucan endotransglycosylase (XET) of Arabidopsis thaliana. XETs endolytically cleave and religate xyloglucan polymers; xyloglucan is one of the primary structural components of the plant cell wall. Therefore, XET function may affect cell shape and plant morphogenesis. To gain insight into the biochemical function of TCH4, we defined structural requirements for optimal XET activity. Recombinant baculoviruses were designed to produce distinct forms of TCH4. TCH4 protein engineered to be synthesized in the cytosol and thus lack normal co- and post-translational modifications is virtually inactive. TCH4 proteins, with and without a polyhistidine tag, that harbor an intact N-terminus are directed to the secretory pathway. Thus, as predicted, the N-terminal region of TCH4 functions as a signal peptide. TCH4 is shown to have at least one disulfide bond as monitored by a mobility shift in SDS-PAGE in the presence of dithiothreitol (DTT). This disulfide bond(s) is essential for full XET activity. TCH4 is glycosylated in vivo; glycosidases that remove N-linked glycosylation eliminated 98% of the XET activity. Thus, co- and/or post-translational modifications are critical for optimal TCH4 XET activity. Furthermore, using site-specific mutagenesis, we demonstrated that the first glutamate residue of the conserved DEIDFEFL motif (E97) is essential for activity. A change to glutamine at this position resulted in an inactive protein; a change to aspartic acid caused protein mislocalization. These data support the hypothesis that, in analogy to Bacillus beta-glucanases, this region may be the active site of XET enzymes.

Animals↗

PubMed1992

Expression of recombinant cytochromes c from various species in Saccharomyces cerevisiae: post-translational modifications.

A complete protocol for the expression of recombinant cytochrome c genes from yeast, Drosophila melanogaster, and rat in a yeast strain, GM-3C-2, which does not express its own cytochromes c is described. The construction of the expression vectors, transformation and large-scale growth of the yeast, and preparation and purification of the recombinant cytochromes c are described. It was found that, contrary to the way yeast modifies its own cytochromes c, the recombinant proteins were partially acetylated at their N-terminus, except for the drosophila protein, which remained entirely unblocked. Furthermore, the yeast and rat proteins were close to fully trimethylated at lysine 72, while the drosophila protein could be separated chromatographically into forms containing tri-, di-, mono-, and unmethylated lysine 72 showing corresponding resonances in the NMR spectrum. These observations emphasize that, in employing expression procedures to obtain native or mutant forms of cytochrome c, it is essential to identify the variety and extent of post-translational modifications and to separate the preparation into pure monomolecular species. Otherwise, it may become impossible to distinguish between the influence of a site-directed mutation and unexamined post-translational modifications.

Amino Acid Sequence↗

PubMed2001

Pleiotropic effects of post-translational modifications on the fate of viral glycopeptides as cytotoxic T cell epitopes.

The fate of viral glycopeptides as cytotoxic T lymphocyte (CTL) epitopes is unclear. We have dissected the mechanisms of antigen presentation and CTL recognition of the peptide GP392-400 (WLVTNGSYL) from the lymphocytic choriomeningitis virus (LCMV) and compared them with those of the previously reported GP92-101 antigen (CSANNSHHYI). Both GP392-400 and GP92-101 bear a glycosylation motif, are naturally N-glycosylated in the mature viral glycoproteins, bind to major histocompatibility complex H-2D(b) molecules, and are immunogenic. However, post-translational modifications differentially affected GP92-101 and GP392-400. Upon N-glycosylation or de-N-glycosylation, a marked decrease in major histocompatibility complex binding was observed for GP392-400 but not for GP92-101. Further, under its N-glycosylated or de-N-glycosylated form, GP392-400 then lost its initial ability to generate a CTL response in mice, whereas GP92-101 was still immunogenic under the same conditions. The genetically encoded form of GP392-400, which on the basis of its immunogenicity could still be presented with H-2D(b) during the course of LCMV infection, does not in fact appear at the surface of LCMV-infected cells. Our results show that post-translational modifications of viral glycopeptides can have pleiotropic effects on their presentation to and recognition by CTL that contribute to either creation of neo-epitopes or destruction of potential epitopes.

Amino Acid Sequence↗

PubMed2002

[Effects of aging and post-translational modifications on molecular chaperone-like activity of alpha-crystalline].

OBJECTIVE: To study the affects of aging and post-translational modifications in vitro on rabbit alpha-crystalline molecular chaperone-like activity. METHODS: (1) Rabbits with three different ages (3 days old, 3 months old and 2 years old) were chosen in the study. The water-soluble crystalline in the three age groups was purified by Sephadex G-200 gel filtration. Different abilities of them to protect beta-low crystalline from thermal aggregation were observed. (2) Incubation of alpha-crystalline with fructose or with H(2)O(2) was carried out for 24 hours. Fructose was used for glycosylation and H(2)O(2) for oxidation of alpha-crystalline. Different abilities of modified and unmodified alpha-crystalline to protect beta-low crystalline from aggregation were observed. RESULTS: (1) alpha-Crystalline of 3 months old rabbit has more ability to protect beta-low crystalline from aggregation than 2 years old rabbit but less ability than 3 days old rabbit. (2) The glycosylated and oxidized alpha-crystalline have less ability to protect beta-low crystalline from aggregation than the unmodified alpha-crystalline. CONCLUSIONS: (1) With aging rabbit alpha-crystallines gradually lose their molecular chaperone-like ability. (2) The modified alpha-crystallines show the loss in molecular chaperone-like ability the most.

Aging↗

PubMed2006

Age-related changes in human crystallins determined from comparative analysis of post-translational modifications in young and aged lens: does deamidation contribute to crystallin insolubility?

We have employed recently developed blind modification search techniques to generate the most comprehensive map of post-translational modifications (PTMs) in human lens constructed to date. Three aged lenses, two of which had moderate cataract, and one young control lens were analyzed using multidimensional liquid chromatography mass spectrometry. In total, 491 modification sites in lens proteins were identified. There were 155 in vivo PTM sites in crystallins: 77 previously reported sites and 78 newly detected PTM sites. Several of these sites had modifications previously undetected by mass spectrometry in lens including carboxymethyl lysine (+58 Da), carboxyethyl lysine (+72 Da), and an arginine modification of +55 Da with yet unknown chemical structure. These new modifications were observed in all three aged lenses but were not found in the young lens. Several new sites of cysteine methylation were identified indicating this modification is more extensive in lens than previously thought. The results were used to estimate the extent of modification at specific sites by spectral counting. We tested the long-standing hypothesis that PTMs contribute to age-related loss of crystallin solubility by comparing spectral counts between the water-soluble and water-insoluble fractions of the aged lenses and found that the extent of deamidation was significantly increased in the water-insoluble fractions. On the basis of spectral counting, the most abundant PTMs in aged lenses were deamidations and methylated cysteines with other PTMs present at lower levels.

Age Factors↗

PubMed2026

Post-Translational Modifications in Traumatic Brain Injury: Decoding the Proteomic Landscape and Molecular Mechanisms of Secondary Injury.

Traumatic brain injury (TBI) initiates a complex secondary injury cascade that significantly contributes to long-term neurological deficits, with post-translational modifications (PTMs) emerging as pivotal molecular regulators of this process. Unlike primary mechanical damage, secondary injury evolves over hours to years and involves intricate proteomic alterations that changes in gene expression alone cannot fully explain. PTMs-including phosphorylation, ubiquitination, acetylation, SUMOylation, glycosylation, and emerging modifications such as succinylation, lactylation, and nitrosylation-serve as dynamic molecular switches that fine-tune protein function, stability, localization, and interactions in response to TBI-induced stressors. These modifications play dual roles: they can either promote neuroprotection and recovery or drive pathological processes such as neuronal cell death (via apoptosis, necroptosis, and ferroptosis), neuroinflammation through glial activation and inflammasome signaling, blood-brain barrier disruption, mitochondrial dysfunction, and impaired synaptic plasticity. Critically, extensive crosstalk exists among different PTM pathways-such as the interplay between phosphorylation and ubiquitination in protein degradation or the competitive balance between acetylation and SUMOylation-that collectively shape cellular fate after injury. This nuanced regulatory network presents both challenges and opportunities for therapeutic intervention. Targeting PTM-related enzymes, including kinases, phosphatases, E3 ligases, and histone deacetylases, has shown promise in preclinical models, while novel strategies like Proteolysis-Targeting Chimeras (PROTACs) and repurposed drugs (e.g., metformin, resveratrol) offer innovative avenues for modulating the PTM landscape. Advances in high-throughput proteomics and mass spectrometry are enabling the mapping of TBI-specific PTM signatures across spatiotemporal phases, facilitating the identification of pro-survival versus pro-death modification thresholds. Despite hurdles in clinical translation-such as blood-brain barrier penetration and off-target effects-the growing understanding of PTM dynamics underscores their potential as both biomarkers and therapeutic targets. Future TBI management may thus rely on precision medicine approaches that integrate multi-PTM profiling to guide combination therapies aimed at tipping the balance toward neural repair and functional recovery.

Brain Injuries, Traumatic↗

PubMed2004

Annotation of post-translational modifications in the Swiss-Prot knowledge base.

High-throughput proteomic studies produce a wealth of new information regarding post-translational modifications (PTMs). The Swiss-Prot knowledge base is faced with the challenge of including this information in a consistent and structured way, in order to facilitate easy retrieval and promote understanding by biologist expert users as well as computer programs. We are therefore standardizing the annotation of PTM features represented in Swiss-Prot. Indeed, a controlled vocabulary has been associated with every described PTM. In this paper, we present the major update of the feature annotation, and, by showing a few examples, explain how the annotation is implemented and what it means. Mod-Prot, a future companion database of Swiss-Prot, devoted to the biological aspects of PTMs (i.e., general description of the process, identity of the modification enzyme(s), taxonomic range, mass modification) is briefly described. Finally we encourage once again the scientific community (i.e., both individual researchers and database maintainers) to interact with us, so that we can continuously enhance the quality and swiftness of our services.

Computational Biology↗

PubMed2004

Post-translational modifications of arabinogalactan-peptides of Arabidopsis thaliana. Endoplasmic reticulum and glycosylphosphatidylinositol-anchor signal cleavage sites and hydroxylation of proline.

We have developed a method for separating the deglycosylated protein/peptide backbones of the small arabinogalactan (AG)-peptides from the larger classical arabinogalactan-proteins (AGPs). AGPs are an important class of plant proteoglycans implicated in plant growth and development. Separation of AG-peptides enabled us to identify eight of 12 AG-peptides from Arabidopsis thaliana predicted from genomic sequences. Of the remaining four, two have low abundance based on expressed sequence tag databases and the other two are only present in pollen (At3g20865) or flowers (At3g57690) and therefore would not be detected in our analysis. Characterization of AG-peptides was performed using matrix-assisted laser desorption ionization-time of flight mass spectrometry and tandem mass spectrometry protein sequencing. These data provide (i) experimental evidence that AG-peptides are processed in vivo for the addition of a glycosylphosphatidylinositol (GPI) anchor, (ii) cleavage site information for both the endoplasmic reticulum secretion signal and the GPI-anchor signal for eight of the 12 AG-peptides, and (iii) experimental evidence that the Gly-Pro motif is hydroxylated in vivo. Furthermore, we show that AtAGP16 is GPI-anchored despite its unusually long hydrophobic C-terminal GPI-signal sequence. Prior to this work, the GPI-anchor cleavage site for only two plant proteins, NaAGP1 from Nicotiana alata and PcAGP1 from Pyrus communis, had been determined experimentally. Characterization of the post-translational modifications of AG-peptides contributes toward obtaining the complete primary structure of this class of biologically important plant proteoglycans and provides a greater understanding of post-translational modifications of plant proteins.

Amino Acid Sequence↗