t-SNARE involved in the molecular regulation of neurotransmitter release. May play an important role in the synaptic function of specific neuronal systems. Associates with proteins involved in vesicle docking and membrane fusion (By similarity). Part of the SNARE core complex containing SNAP25, VAMP2 and STX1A. This complex binds CPLX1. Interacts with TRIM9, RIMS1 and SNAPIN. Binds STXBP6. Found in a ternary complex with STX1A and VAMP8. Associates with the BLOC-1 complex. Isoform 1 and isoform 2 interact with BLOC1S6 (By similarity). Interacts with alpha-synuclein/SNCA (By similarity). Membrane association requires palmitoylation. Isoforms differ by the usage of two alternative homologous exons (5a and 5b) which code for positions 56 to 94 and differ only in 9 positions out of 39. Palmitoylated. Cys-85 appears to be the main site, and palmitoylation is required for membrane association (By similarity). Belongs to the SNAP-25 family.