Calcium-dependent interaction of the cytoplasmic region of synaptotagmin with membranes. Autonomous function of a single C2-homologous domain.
Year: 1994
Type: article
Abstract: The synaptic vesicle protein synaptotagmin has been implicated in the docking and subsequent calcium-regulated exocytosis of synaptic vesicles. We demonstrate that synaptotagmin is a major constituent of synaptic vesicle membranes, comprising 7-8% of the total vesicle protein. A proteolytic fragment of synaptotagmin, containing two repeats homologous to the C2-domain of protein kinase C, bound to a variety of natural membranes in a calcium-dependent manner (EC50 approximately 30 microM calcium). Binding was insensitive to proteolysis of the acceptor membranes suggesting an interaction with the lipid constituents. This interaction was confirmed using a recombinant fusion protein, containing both C2-like domains of synaptotagmin, that bound to artificial liposomes in a calcium-dependent manner. Phospholipid binding properties were preserved in a 114-amino acid domain corresponding to the first C2-like repeat of the protein and represents the shortest functional cassette yet reported. Furthermore, deletion of a highly conserved 9-amino acid motif, within this region, was sufficient to abolish the calcium-dependent phospholipid binding properties of this domain. This mutation may provide a means to selectively disrupt individual C2-domains in order to assess their relative contributions to function.
Source: Journal of Biological Chemistry
Authors: E.R. Chapman, R. Jahn
Institutions: Howard Hughes Medical Institute, Yale University
Language: English
Subfield: Cell Biology
Domain: Life Sciences
Open Access status: hybrid
Estimated APC paid: $3,430
OpenAlex ID: W1568294354