A role for synaptotagmin (p65) in regulated exocytosis.
Proteins that are specifically localized to synaptic vesicles in the nervous system have been proposed to mediate aspects of synaptic transmission. Antibodies raised against the cytoplasmic domains of five of these proteins, vamp, rab3A, synaptophysin, synaptotagmin, and SV2, were used to investigate their function. Microinjection of monoclonal and polyclonal antibodies raised against synaptotagmin (p65), but not the other vesicle proteins, decreases K+/Ca(2+)-mediated dopamine beta-hydroxylase surface staining, a measure of regulated secretion in PC12 cells. Microinjection of a soluble fragment of synaptotagmin encompassing one of the domains homologous to the C2 regulatory region of protein kinase C, but lacking the membrane anchor, also inhibits evoked dopamine beta-hydroxylase surface staining. These results provide support for the hypothesis that synaptotagmin, a Ca(2+)- and phospholipid-binding protein, is important for regulated exocytosis in neurons.
Elferink
L A
LA
Howard Hughes Medical Institute, Department of Molecular and Cellular Physiology, Stanford University, California 94305.
Peterson
M R
MR
Scheller
R H
RH
D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000276:immunology; D002135:Calcium-Binding Proteins; D004299:Dopamine beta-Hydroxylase / Q000378:metabolism; D005089:Exocytosis / Q000502:physiology*; D005455:Fluorescent Antibody Technique; D008562:Membrane Glycoproteins / Q000276:immunology / Q000502:physiology*; D008845:Microinjections; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000276:immunology / Q000502:physiology*; D009474:Neurons / Q000502:physiology; D016716:PC12 Cells; D051381:Rats; D012995:Solubility; D050863:Synaptotagmin I; D050857:Synaptotagmins
D000906:Antibodies; D002135:Calcium-Binding Proteins; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; D050863:Synaptotagmin I; D050857:Synaptotagmins; D004299:Dopamine beta-Hydroxylase