title: Synaptotagmin I- and II-deficient PC12 cells exhibit calcium-independent, depolarization-induced neurotransmitter release from synaptic-like microvesicles.
abstract: Synaptotagmin I- and II-deficient PC12 cells (Shoji-Kasai et al. [1]) were used to compare the role of this protein in the calcium-dependent exocytosis of secretory granules and synaptic-like microvesicles (SLMVs). While neither catecholamine nor protein secretion from secretory granules were altered, the depolarization-induced acetylcholine release from SLMVs was no longer calcium-dependent. We propose that within the exocytotic process of SLMVs, there exist two depolarization-induced steps. One is calcium-dependent and no longer present in synaptotagmin I- and II-deficient cells. The other is induced by depolarization, does not require calcium, and suffices to trigger neurotransmitter release from SLMVs in synaptotagmin I- and II-deficient PC12 cells.
authors.affiliation: Institute for Neurobiology, University of Heidelberg, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Bauerfeind
authors.forename: R
authors.initials: R
authors.lastname: Jelinek
authors.forename: W B
authors.initials: WB
authors.lastname: Huttner
mesh_terms: D000109:Acetylcholine / Q000378:metabolism; D000200:Action Potentials; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002135:Calcium-Binding Proteins; D002499:Centrifugation, Density Gradient; D002794:Choline / Q000378:metabolism; D003594:Cytoplasmic Granules / Q000378:metabolism; D005089:Exocytosis; D008562:Membrane Glycoproteins / Q000172:deficiency / Q000502:physiology*; D009419:Nerve Tissue Proteins / Q000172:deficiency / Q000502:physiology*; D018377:Neurotransmitter Agents / Q000378:metabolism*; D016716:PC12 Cells; D051381:Rats; D013572:Synaptic Vesicles / Q000378:metabolism*; D050863:Synaptotagmin I; D050861:Synaptotagmin II; D050857:Synaptotagmins; D014316:Tritium
chemical_list: D002135:Calcium-Binding Proteins; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; D018377:Neurotransmitter Agents; D050863:Synaptotagmin I; D050861:Synaptotagmin II; C494312:Syt1 protein, rat; C494264:Syt2 protein, rat; D014316:Tritium; D050857:Synaptotagmins; D002794:Choline; D000109:Acetylcholine; D002118:Calcium