1998 Fiscal Year Final Research Report Summary
Role of the cytoplasmic protein synaphin in the process of transmitter release
| Project/Area Number |
09680760
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Neurochemistry/Neuropharmacology
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| Research Institution | Niigata University |
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Principal Investigator |
ABE Teruo Niigata University Brain Research Institute, Associate Professor, 脳研究所, 助教授 (50010103)
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| Project Period (FY) |
1997 – 1998
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| Keywords | Synaphin / Transmitter release / Syntaxin / Synapse |
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| Research Abstract |
Synaphin is a cytosolic protein we first found to be associated with the docking/fusion complex that is critical to transmitter release. The goal of this study was to clarify the function of this protein in the release process. We have obtained following results.
(1) Distribution in the brain and tevolutionary conservation
Two isoforms of synaphin (synaphins 1 and 2 : 84% identical) exist in the brain. The two isoforms are distictly distributed in the brain regions such as cerebral cortex, thalamus, cerebellum and amygdaloid., indicating different physiological implications for the isoforms. Synaphins very similar to mammalian ones are present in fish, and an invertebrate nervous system also contains the proteins.
(2) Function
When a peptide corresponding to a partial amino acid sequence of synaphin was injected into the presynaptic terminal of the squid giant synapse, transmitter release was rapidly inhibited. This peptide inhibited binding of synaphin to syntaxin but did not affect SNARE interactions, synaptic vesicle docking or calcium channel functions. Thus synaphin/syntaxin interaction is essential for transmitter release. In vitro binding experiments between recombinant SNARE proteins and synaphin show that syntaxin alone binds very little synaphin. However, the synaptic vesicle protein VAMP (synaptobrevin) markedly facilitated syntaxin binding to synaphin. Conversely, synaphin geatly increased the affinity of VAMP to syntaxin. Taken together, these results indicate that synaphin/SNARE interactions play an essential role at a step between synaptic vesicle docking and fusion.
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