Multiple structural states in an intrinsically disordered protein, SNAP-25, using circular dichroism.

SNAP-25, together with other SNARE proteins, drives fusion of synaptic vesicles with the nerve cell membrane, leading to neurotransmitter release. It is unique in contributing two α helices to the four-helix bundle known as the SNARE complex. Complex formation drives fusion as these proteins transform from a disordered to ordered (coiled-coil) state.