title: Palmitoylation sites and processing of synaptotagmin I, the putative calcium sensor for neurosecretion.
abstract: Synaptotagmin I, the calcium sensor for neurotransmission, is palmitoylated. We have identified the palmitoylation sites as five cysteine residues located between the transmembrane and cytoplasmic regions. In contrast to wild-type synaptotagmin, the non-acylated mutant is not converted to the endoglycosidase-H-resistant form after expression in CV-1 cells. This indicates a block in transport through the Golgi complex. However, when expressed in PC-12 and RBL cells non-acylated synaptotagmin is targeted to the plasma membrane and to secretory granules. No significant cleavage of [(3)H]palmitate from synaptotagmin was observed in pulse-chase experiments. This indicates that the majority of fatty acids are structural rather than dynamic components.
authors.affiliation: Department of Immunology and Molecular Biology, Veterinary-Medical Faculty, Free University Berlin, Philippstrasse 13, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Heindel
authors.forename: Michael F G
authors.initials: MF
authors.lastname: Schmidt
authors.forename: Michael
authors.initials: M
authors.lastname: Veit
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins; D002460:Cell Line; D003545:Cysteine / Q000737:chemistry; D004247:DNA / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D005227:Fatty Acids / Q000737:chemistry; D019084:Fluorescent Antibody Technique, Indirect; D006031:Glycosylation; D006056:Golgi Apparatus / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry; D008969:Molecular Sequence Data; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000378:metabolism; D016716:PC12 Cells; D019308:Palmitic Acid / Q000737:chemistry* / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D051381:Rats; D017386:Sequence Homology, Amino Acid; D050825:Synaptosomal-Associated Protein 25; D050863:Synaptotagmin I; D050857:Synaptotagmins; D013997:Time Factors; D014407:Tumor Cells, Cultured
chemical_list: D002135:Calcium-Binding Proteins; D005227:Fatty Acids; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; C494210:Snap25 protein, rat; D050825:Synaptosomal-Associated Protein 25; D050863:Synaptotagmin I; C494312:Syt1 protein, rat; D050857:Synaptotagmins; D019308:Palmitic Acid; D004247:DNA; D003545:Cysteine; D002118:Calcium