SUBCELLULAR LOCATION: Endosome membrane {ECO:0000256|ARBA:ARBA00004125}; Peripheral membrane protein {ECO:0000256|ARBA:ARBA00004125}; Cytoplasmic side {ECO:0000256|ARBA:ARBA00004125}. Late endosome membrane {ECO:0000256|ARBA:ARBA00004492}; Peripheral membrane protein {ECO:0000256|ARBA:ARBA00004492}; Cytoplasmic side {ECO:0000256|ARBA:ARBA00004492}. Lysosome membrane {ECO:0000256|ARBA:ARBA00004630}; Peripheral membrane protein {ECO:0000256|ARBA:ARBA00004630}; Cytoplasmic side {ECO:0000256|ARBA:ARBA00004630}. SIMILARITY: Belongs to the STXBP/unc-18/SEC1 family. {ECO:0000256|ARBA:ARBA00009884}. |