EXTENSIVE LIPIDATION OF A TORPEDO CYSTEINE STRING PROTEIN

Cysteine string proteins are relatively low mass components of synapti c vesicle membranes. Structurally, their primary sequence is distingui shed by a remarkable, cysteine-rich motif. Investigations revealed an unprecedented degree of lipidation of these cysteine residues. At leas t 11 of the 13 cysteines of the Torpedo protein were modified, princip ally by palmitoyl moieties. This fatty acylation creates a prominent h ydrophobic domain flanked by polar amino and carboxyl termini. An amph ipathic 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.