Synapsin I (protein I), a nerve terminal-specific phosphoprotein. I. Its general distribution in synapses of the central and peripheral nervous system demonstrated by immunofluorescence in frozen and plastic sections.

Abstract

Synapsin I (formerly referred to as protein I) is the collective name for two almost identical phosphoproteins, synapsin la and synapsin Ib (protein la and protein Ib), present in the nervous system. Synapsin I has previously been shown by immunoperoxidase studies (De Camilli, P., T. Ueda, F. E. Bloom, E. Battenberg, and P. Greengard, 1979, Proc. Natl. Acad. ScL USA, 76:5977-5981; Bloom, F. E., T. Ueda, E. Battenberg, and P. Greengard, 1979, Proc. Natl. Acad. 5ci. USA 76:5982-5986) to be a neuron-specific protein, present in both the central and peripheral nervous systems and concentrated in the synaptic region of nerve cells. In those preliminary studies, the occurrence of synapsin I could be demonstrated in only a portion of synapses. We have now carried out a detailed examination of the distribution of synapsin I immunoreactivity in the central and peripheral nervous systems. In this study we have attempted to maximize the level of resolution of immunohistochemical light microscopy images in order to estimate the proportion of immunoreactive synapses and to establish their precise distribution. Optimal results were obtained by the use of immunofluorescence in semithin sections (~1 #m) prepared from Epon-embedded nonosmicated tissues after the Epon had been removed.Our results confirm the previous observations on the specific localization of synapsin I in nerve cells and synapses. In addition, the results strongly suggest that, with a few possible exceptions involving highly specialized neurons, all synapses contain synapsin I. Finally, immunocytochemical experiments indicate that synapsin I appearance in the various regions of the developing nervous system correlates topographically and temporally with the appearance of synapses.In two accompanying papers (De Camilli, P., S. M. Harris, Jr., W. B. Huttner, and P. Greengard, and Huttner, W. B., W. Schiebler, P. Greengard, and P. De Camilli, 1983, J. Cell Biol. 96:1355-1373 and 1374-1388, evidence is presented that synapsin I is specifically associated with synaptic vesicles in nerve endings.Synapsin I (formerly referred to as protein I) is the collective name for two peptides, synapsin Ia and synapsin Ib (protein Ia and protein Ib) with very similar properties. It was discovered as a major endogenous substrate for cAMP-dependent phosphorylation in mammalian brain (26,50). Later studies showed that synapsin I is also a major endogenous substrate for Ca/ calmodulin-dependent phosphorylation in brain (22,23,27,28,46). Synapsin I has been purified to homogeneity from

Cellular distribution and subcellular localization of molecular components of vesicular transmitter release in horizontal cells of rabbit retina

“…Two antibodies to synapsin I were used: a rabbit polyclonal antibody (1:500 -1:2,000; P610; DeCamilli et al, 1983;Geppert et al, 1994;von Kriegstein et al, 1999) and a mouse monoclonal antibody (1:100; Chemicon, Temecula, CA; MAB355; Smith et al, 1993). The specificity of both has been demonstrated on Western blots, and preabsorption of the antibody with purified synapsin I resulted in a block of immunolabeling (De Camilli et al, 1983;Smith et al, 1993). In addition, double-label experiments with the two synapsin I antibodies produced a complete co-localization of immunoreactivity (data not shown).…”

“…Vibratome sections were cut at 50 m into cold PBS, pH 7.4. The primary antibodies were used in the same concentration and diluted in the same media used for light microscopy, except that Triton X-100 was 1:2,500-1:5,000 GABA Rat GABA conjugated to thyroglobulin w/PFA D. Pow, Brisbane, Australia (Pow et al, 1995) 1:200 Glycine Rat Glycine conjugated to thyroglobulin w/PFA D. Pow (Pow et al, 1995) 1:1,000 Syntaxin-1/HPC-1 Mouse Hippocampal plasma membranes (HPC) Sigma, S0664 (Barnstable et al, 1985;Inoue et al, 1992) 1:2,500 Synapsin 1 Rabbit Purified bovine synapsin 1 H. Betz, Frankfurt, Germany (De Camilli et al, 1983;Geppert et al, 1994;von Kriegstein et al, 1999) 1:500-2,000…”

Expression of Neuronal Kinesin Heavy Chain Is Developmentally Regulated in the Central Nervous System of the Rat

“…Two P1, two P7, four P15, and six adult rats were anesthetized with an intraperitoneal injection of either chloral hydrate (500 mg/kg) or a mixture of xylazine (10 mg/kg; Rompun; Bayer AG, Leverkusen, Germany) and ketamine (50 mg/kg; Inoketam 500; Virbac, France) and fixed by transcardial perfusion as previously described (Dc Camilli et al, 1983;Niclas Ct al., 1994).…”

Synapsin I and Synaptophysin expression during ontogenesis of the mouse peripheral vestibular system

“…The antibodies were all affinity-purified and thoroughly characterized (De Camilli et al, 1983;Jahn et al, 1985;Navonc et al, 1986). The specificity of the immunocytochemical reactions was assessed by incubation of 1 section per experiment with nonimmune serum instead of the specific primary antibody.…”

“…However Synapsin I and Synaptophysin are usually not detectable by immunocytochemistry in CNS dendrites, whereas they are highly concentrated in axonal endings where they probably participate in the regulation of the release of neurotransmitter (De Camilli and Jahn, 1990). In axonal endings, Synapsin I is selectively associated with neurotransmitter-containing small synaptic vesicles (SSVs;De Camilli et al, 1983;Navone et al, 1984) and interact with various cytoskeletal elements (Balher and Greengard, 1987). Synaptophysin is an intrinsic membrane protein of axonal endings' SSVs (Jahn et al, 1985;Navone et al, 1986).…”