Syntaxin 4 (STX4)

STX4A, a syntaxin gene isolated from a placenta library. (The gene was previously symbolized STX2.) It encodes a predicted 297-amino acid protein that is 89% identical to the amino acid sequence of rat Stx4a.The molecular mechanisms responsible for targeting of vesicles containing aquaporin-2 (AQP2) to the apical plasma membrane of renal collecting duct cells may involve the vesicle-targeting protein STX4. Among the known syntaxin isoforms, only STX1 (STX1A) and STX4 bind VAMP2 with high affinity. Thus, STX1 and STX4 could be considered candidates for a role in targeting of the AQP2/VAMP2-containing vesicles to the apical plasma membrane in collecting duct cells. In contrast to STX1, which is expressed predominantly in the central nervous system, STX4 is expressed in a variety of tissues including the kidney.