Extensive lipidation of a Torpedo cysteine string protein.

Cysteine string proteins are relatively low mass components of synaptic vesicle membranes. Structurally, their primary sequence is distinguished by a remarkable, cysteine-rich motif. Investigations revealed an unprecedented degree of lipidation of these cysteine residues. At least 11 of the 13 cysteines of the Torpedo protein were modified, principally by palmitoyl moieties. This fatty acylation creates a prominent hydrophobic domain flanked by polar amino and carboxyl termini. An amphipathic structure of this type is uniquely suited to mediate events at membrane interfaces. Thus, cysteine string proteins are candidates to participate in exocytotic membrane fusion.