Multiple palmitoylation of synaptotagmin and the t-SNARE SNAP-25.

Synaptotagmin, a likely calcium sensor for synaptic transmission, and SNAP-25, a t-SNARE of the presynaptic plasma membrane, are key proteins for the docking and fusion of synaptic and other vesicles. We report that both synaptotagmin and SNAP-25 are palmitoylated with their fatty acids attached in a labile thioester-type bond. A SNAP-25 mutant with deleted palmitoylation sites is found exclusively in the cytosol after cell fractionation, whereas the palmitoylated form of SNAP-25 is membrane-bound, establishing that SNAP-25 is membrane-anchored via covalently linked palmitate.