Palmitoylation sites and processing of synaptotagmin I, the putative calcium sensor for neurosecretion.
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.
Heindel
Ulrich
U
Department of Immunology and Molecular Biology, Veterinary-Medical Faculty, Free University Berlin, Philippstrasse 13, Germany.
Schmidt
Michael F G
MF
Veit
Michael
M
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
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