Acts as a general chaperone in regulated exocytosis (By similarity). Acts as a co-chaperone for the SNARE protein SNAP-25 (By similarity). Involved in the calcium-mediated control of a late stage of exocytosis (By similarity). May have an important role in presynaptic function. May be involved in calcium-dependent neurotransmitter release at nerve endings (By similarity).
Subcellular locations: Cytoplasm, Cytosol, Membrane, Cytoplasmic vesicle, Secretory vesicle, Chromaffin granule membrane, Melanosome, Cell membrane
The association with membranes is regulated by palmitoylation (By similarity). Identified by mass spectrometry in melanosome fractions from stage I to stage IV .
Expressed in pancreas, kidney, skeletal muscle, liver, lung, placenta, brain and heart.