Glycoproteins of the Synapse

Gurd, James W.

doi:10.1007/978-1-4757-5955-6_7

Cited by 8 publications

(7 citation statements)

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“…sis, suggesting a role for tyrosine phosphorylation in the formation or maturation of synapses (Gurd and Bissoon, 1990;Cudmore and Gurd, 1991). As part of our continuing analysis of the role of glycoproteins in synaptic function (Gurd, 1989), we previously reported that the PSD-associated glycoprotein, PSD-GP180, is phosphorylated on tyrosine residues both in vivo and in vitro (Gurd, 1985;Gurd and Bissoon, 1985). We now describe the tyrosine phosphorylation of glycoproteins in the adult and developing brain and provide evidence that the major tyrosine-phosphorylated glycoprotein present in brain homogenates corrcsponds to PSD-GP180.…”

Section: Gel Electrophoresis and Immunoblottingmentioning

confidence: 96%

Tyrosine phosphorylation of glycoproteins in the adult and developing rat brain

Soulliere

Bissoon

Khurgel

et al. 1994

J of Neuroscience Research

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The tyrosine phosphorylation of glycoproteins in the adult and developing rat brain was investigated. Immunoblotting with anti-tyr(P) antibodies identified a glycoprotein with an apparent Mr of 180,000 (GP180) as the major tyrosine-phosphorylated protein in the concanavalin A (con A)-binding fraction prepared from forebrain homogenates. This glycoprotein had the same electrophoretic mobility as the postsynaptic density (PSD)-associated glycoprotein PSD-GP180. Tyrosine-phosphorylated GP180 was enriched 24-fold in isolated PSDs relative to homogenates. Digestion with endoglycosidase F/N-glycosidase F demonstrated that GP180 present in total homogenates and PSD-GP180 present in isolated PSDs contained similar amounts of N-linked oligosaccharide suggesting that they are the same glycoprotein. The tyrosine phosphorylation of GP180 in homogenates varied between brain regions with the highest levels occurring in cortical areas and the amygdala and low or undetectable amounts being present in hindbrain regions. Incubation of homogenates with adenosine triphosphate (ATP) resulted in the tyrosine phosphorylation of GP180 in all regions examined except the cerebellum and identified a second con A-binding glycoprotein, GP110, which was phosphorylated on tyrosine. GP180 was not phosphorylated on tyrosine following the incubation of cerebellar homogenate, synaptic membranes, or PSDs and ATP. Tyr(P)-GP180 was not detected prior to the onset of synaptogenesis, increased in parallel with the formation of synapses during the first 4 weeks of postnatal development of the frontal cortex and hippocampus, and then decreased 50-60% to adult levels. The results suggest that GP180 corresponds to the PSD glycoprotein PSD-GP180 and are consistent with a role for this glycoprotein in synaptic development and signal transduction at the synapse.

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Section: Gel Electrophoresis and Immunoblottingmentioning

confidence: 96%

Tyrosine phosphorylation of glycoproteins in the adult and developing rat brain

Soulliere

Bissoon

Khurgel

et al. 1994

J of Neuroscience Research

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“…The cellular components of the synapse, the presynaptic and postsynaptic nerve terminals, and the extracellu lar matrix material in the synaptic cleft are key elements for synaptogenesis [1,2], Glycoconjugates, which in clude glycoprotein cell adhesion molecules and proteo glycans, are abundant components of the pre-and post synaptic structures [3,4]. O f the carbohydrate structures present on the glycoconjugates, sialic acid, N-acetyllaclosamine, 3-1,3-N-acetylgalactosamine and a-L-fucosyl residues are of particular interest as regulators of neural cell adhesion, nerve growth and neurite branching, as well as establishing boundaries throughout the neuraxis in the embryonic and postnatal periods [5][6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Synaptic Vesicle and Synaptic Membrane Glycoproteins during Pre- and Postnatal Development of Mouse Cerebral Cortex, Cerebellum and Spinal Cord

Mayanil

Knepper

1993

Dev Neurosci

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Glycoproteins of synaptic vesicles and synaptic membranes play an important role during the process of synaptogenesis. In order to study the temporal expression of specific carbohydrates and the expression of selected neural proteins, we used peroxidase-conjugated lectin overlays on Western blots and immunoblots of synaptic vesicles and synaptic membranes isolated from pre- and postnatal mouse cerebral cortex, cerebellum and spinal cord. Our lectin overlays on Western blots showed that (1) the synaptic vesicle glycoproteins, gp80–100, gp47 and gp44, and (2) the synaptic membrane glycoproteins, gp180, gp72, gp70 and gp34, show temporal regulation of expression of carbohydrate moieties. Quite significantly, gp47 showed a decrease in the vesicles coinciding with an increase in membranes suggesting a shift in localization. Anti neural cell adhesion molecule (N-CAM) antibody cross-reacted with gp180. The developmental expression of synaptotagmin 1, a well characterized glycoprotein of synaptic vesicle, was determined by immunoblots analysis. Anti synaptosomal-associated protein 25 (SNAP-25) antibody immunoblots were performed in order to compare our results with a developmentally regulated synaptosomal protein demonstrating expression coincident with synaptogenesis. Our immunoblot studies showed that (1) N-CAM (gp180) immunoreactivity decrease with development; (2) the expression of synaptotagmin 1 and SNAP-25 increases as development progresses, and (3) synaptotagmin 1 and SNAP-25 show a shift in subcellular localization (from synaptic vesicle to synaptic membrane) during development, thereby indicating that these proteins are first identified in a vesicular fraction. Thus, our data suggest that synaptic vesicle and synaptic membrane glycoproteins show temporal regulation of specific carbohydrates as well as protein expression during development, which may be a key factor to our understanding of the process of synaptogenesis.

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“…Lectin overlay studies (Fu et al,198 1) and use of biotinylated lectin probes (Gordon-Weeks and Harding, 1983) show that synaptic membrane (SM) fractions are enriched in some 20 con A binding glycoproteins. Postsynaptic densities (psds) are selectively enriched in a number of these glycoproteins, particularly species with molecular masses of 180, 145, 116, and 110 kDa (Gurd, 1980(Gurd, , 1989. However, few synaptic glycoproteins are well characterised and very little is known concerning the function of these molecules.…”

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confidence: 99%

Molecular Characterisation and Structural Relationship of the Synapse‐Enriched Glycoproteins gp65 and gp55

Willmott

Skitsa

Hill

et al. 1992

Journal of Neurochemistry

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gp65 and gp55 are glycoprotein components of CNS synapses that are recognised by a single monoclonal antibody, SMgp65. This antibody has now been used to investigate the molecular properties of these two glycoproteins and the structural relationship between them. Both gp65 and gp55 occur in most brain regions as doublets of apparent molecular masses of 63 and 67 kDa, and 52 and 57 kDa, respectively. Striatal samples, however, are enriched in a novel gp65 isoform of 69 kDa. Removal of oligosaccharide residues from gp65 and gp55 with trifluoromethanesulphonic acid shows that gp65 and gp55 are composed of single polypeptide chains of 40 and 28 kDa, respectively. Removal of sialic acid residues with neuraminidase lowers the apparent molecular mass of both glycoproteins by 5-6 kDa. Triton X-114 phase partitioning and alkaline extraction of synaptic membranes indicate that both gp65 and gp55 are integral membrane glycoproteins. Treatment of synaptic membranes with phosphatidylinositol-specific phospholipase C does not solubilise either glycoprotein. One-dimensional peptide and epitope maps obtained by digestion of gp65 and gp55 with endoproteinase lys C or subtilisin are consistent with a close structural relationship between the two molecules. Tryptic digestion of samples enriched in gp65 and/or gp55 results in the formation of a novel immunoreactive 53-kDa species that is resistant to further trypsin degradation except in the presence of 0.1% (wt/vol) sodium dodecyl sulphate. Trypsin treatment of cultures of forebrain neurones in situ lowers the apparent molecular mass of gp65 to 53 kDa.(ABSTRACT TRUNCATED AT 250 WORDS)

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Glycoproteins of the Synapse

Cited by 8 publications

References 149 publications

Tyrosine phosphorylation of glycoproteins in the adult and developing rat brain

Tyrosine phosphorylation of glycoproteins in the adult and developing rat brain

Synaptic Vesicle and Synaptic Membrane Glycoproteins during Pre- and Postnatal Development of Mouse Cerebral Cortex, Cerebellum and Spinal Cord

Molecular Characterisation and Structural Relationship of the Synapse‐Enriched Glycoproteins gp65 and gp55

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