Synaptotagmin III is a novel isoform of rat synaptotagmin expressed in endocrine and neuronal cells.
1994; Elsevier BV; Volume: 269; Issue: 16 Linguagem: Inglês
10.1016/s0021-9258(17)32622-4
ISSN1083-351X
AutoresMasanari Mizuta, Nobuya Inagaki, Y Nemoto, Shigeru Matsukura, Masayuki Takahashi, Susumu Seino,
Tópico(s)Erythrocyte Function and Pathophysiology
ResumoSynaptotagmin (p65), an integral membrane protein of synaptic vesicles, is thought to be involved in calciumdependent exocytosis of synaptic vesicles.Here, we report the cloning and tissue distribution of a novel isoform of synaptotagmin, designated synaptotagmin 111.The cDNA clones encoding synaptotagmin I11 have been isolated from a rat brain cDNA library.Rat synaptotagmin I11 is a protein of 588 amino acids having 40.5,38.3,and 64.0%identity with rat synaptotagmin I, rat synaptotagmin 11, and o-p65-c, a third synaptotagmin isoform of marine ray Discopyge ommata, respectively.The region of the two internal repeats homologous to the regulatory domain (C, domain) of protein kinase C is highly conserved among synaptotagmin I, 11, and 111.RNA blotting studies reveal that synaptotagmin I11 mRNA is expressed in brain, various endocrine tissues, and hormone-secreting clonal cells.These results suggest that rat synaptotagmin I11 is a mammalian homolog of o-p65-c and is involved in Ca2+-dependent exocytosis of secretory vesicles in endocrine cells, as well as in neurons.Intracellular calcium is a pivotal signal in hormone and neurotransmitter release from endocrine and neuronal cells.The intracellular calcium concentration ([Ca"],) in these cells has
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