Abstract
Synaptotagmin I is localized to synaptic vesicles where it functions in the calcium-triggered release of neurotransmitters. Here we demonstrate that synaptotagmin I covalently incorporated [3H]palmitate after metabolic labelling of PC-12 cells and rat brain synaptosomes. Labeling was localized to a tryptic fragment that contains a cluster of cysteine residues adjacent to the molecule's single transmembrane anchor. Neutral hydroxylamine released the [3H]palmitate from this fragment and increased its electrophoretic mobility, demonstrating that acylation occurs at the membrane-proximal cysteine cluster. In addition, hydroxylamine-induced mobility shifts were also apparent for synaptotagmins II and III, suggesting that posttranslational palmitoylation via thioester bonds may be a general modification of all synaptotagmins.
MeSH terms
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Acylation
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Amino Acid Sequence
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Animals
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Aplysia
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Brain / metabolism*
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Caenorhabditis elegans
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Calcium-Binding Proteins*
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Cysteine
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Decapodiformes
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Drosophila
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Humans
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Hydroxylamine
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Hydroxylamines / pharmacology
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Membrane Glycoproteins / chemistry*
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Membrane Glycoproteins / isolation & purification
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Membrane Glycoproteins / metabolism*
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Molecular Sequence Data
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Nerve Tissue Proteins / chemistry*
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Nerve Tissue Proteins / isolation & purification
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Nerve Tissue Proteins / metabolism*
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PC12 Cells
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Palmitic Acid
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Palmitic Acids / metabolism*
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Rats
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Sequence Homology, Amino Acid
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Synaptosomes / metabolism*
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Synaptotagmin I
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Synaptotagmins
Substances
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Calcium-Binding Proteins
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Hydroxylamines
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Membrane Glycoproteins
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Nerve Tissue Proteins
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Palmitic Acids
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SYT1 protein, human
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Synaptotagmin I
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Syt1 protein, rat
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Synaptotagmins
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Hydroxylamine
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Palmitic Acid
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Cysteine