RRC ID 48557
Author Fukuda M, Kanno E, Mikoshiba K.
Title Conserved N-terminal cysteine motif is essential for homo- and heterodimer formation of synaptotagmins III, V, VI, and X.
Journal J Biol Chem
Abstract The synaptotagmins now constitute a large family of membrane proteins characterized by one transmembrane region and two C2 domains. Dimerization of synaptotagmin (Syt) I, a putative low affinity Ca(2+) sensor for neurotransmitter release, is thought to be important for expression of function during exocytosis of synaptic vesicles. However, little is known about the self-dimerization properties of other isoforms. In this study, we demonstrate that a subclass of synaptotagmins (III, V, VI, and X) (Ibata, K., Fukuda, M., and Mikoshiba, K. (1998) J. Biol. Chem. 273, 12267-12273) forms beta-mercaptoethanol-sensitive homodimers and identify three evolutionarily conserved cysteine residues at the N terminus (N-terminal cysteine motif, at amino acids 10, 21, and 33 of mouse Syt III) that are not conserved in other isoforms. Site-directed mutagenesis of these cysteine residues and co-immunoprecipitation experiments clearly indicate that the first cysteine residue is essential for the stable homodimer formation of Syt III, V, or VI, and heterodimer formation between Syts III, V, VI, and X. We also show that native Syt III from mouse brain forms a beta-mercaptoethanol-sensitive homodimer. Our results suggest that the cysteine-based heterodimerization between Syt III and Syt V, VI, or X, which have different biochemical properties, may modulate the proposed function of Syt III as a putative high affinity Ca(2+) sensor for neurotransmitter release.
Volume 274(44)
Pages 31421-7
Published 1999-10-29
DOI 10.1074/jbc.274.44.31421
PMID 10531343
MeSH Amino Acid Motifs Amino Acid Sequence Animals Calcium-Binding Proteins* Conserved Sequence Cysteine* / genetics Dimerization Membrane Glycoproteins / chemistry* Membrane Glycoproteins / classification Membrane Glycoproteins / genetics Membrane Glycoproteins / metabolism* Mice Molecular Sequence Data Mutagenesis, Site-Directed Nerve Tissue Proteins / chemistry* Nerve Tissue Proteins / classification Nerve Tissue Proteins / genetics Nerve Tissue Proteins / metabolism* Phylogeny Protein Binding Recombinant Proteins / chemistry Recombinant Proteins / metabolism Sequence Homology, Amino Acid Synaptotagmins
IF 4.106
Times Cited 144
DNA material pEF-T7-Syt III (Syt3) (RDB14683) pEF-T7-Syt IV (Syt4) (RDB14684) pEF-T7-Syt V (Syt9) (RDB14685) pEF-T7-Syt VI (Syt6) (RDB14686) pEF-T7-Syt VII (Syt7) (RDB14687) pEF-T7-Syt VIII (Syt8) (RDB14688) pEF-T7-Syt IX (Syt5) (RDB14689) pEF-T7-Syt X (Syt10) (RDB14690) pEF-T7-Syt XI (Syt11) (RDB14691).