A TARGETING SIGNAL IN VAMP REGULATING TRANSPORT TO SYNAPTIC VESICLES

VAMP is a synaptic vesicle membrane protein required for fusion. Synap tic vesicle targeting was measured for mutants of an epitope-tagged fo rm of VAMP in transfected PC12 cells. A signal within a predicted amph ipathic alpha helix is essential for targeting to synaptic vesicles. C ellubrevin, a nonneural VAMP homolog, contains this signal and is also targeted to synaptic vesicles. Amino acid substitutions within the sy naptic vesicle targeting signal either enhance or inhibit sorting of V AMP to synaptic vesicles, but do not affect the ability of VAMP to for m complexes with syntaxin and SNAP-25.