Synaptic vesicle and synaptic membrane glycoproteins during pre-and postnatal development of mouse cerebral cortex, cerebellum and spinal cord

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, gp 180, 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-re-acted with gpl80. 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 (gp 180) 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.