Members of this family, which are found in the amino terminus of various SNARE proteins, adopt a structure consisting of an antiparallel three-helix bundle. Their exact function has not been determined, though it is known that they regulate the SNARE motif, as well as mediate various protein-protein interactions involved in membrane-transport [1].

1: Three-dimensional structure of the amino-terminal domain of syntaxin 6, a SNAP-25 C homolog. Misura KM, Bock JB, Gonzalez LC Jr, Scheller RH, Weis WI; Proc Natl Acad Sci U S A. 2002;99:9184-9189. PMID:12082176