Involved in the targeting and/or fusion of transport vesicles to their target membrane during transport of proteins from the early endosome to the lysosome. Required for heterotypic fusion of late endosomes with lysosomes and homotypic lysosomal fusion. Required for calcium regulated lysosomal exocytosis. Involved in the export of chylomicrons from the endoplasmic reticulum to the cis Golgi. Required for exocytosis of mediators during eosinophil and neutrophil degranulation, and target cell killing by natural killer cells. Required for focal exocytosis of late endocytic vesicles during phagosome formation.
Subcellular locations: Cytoplasmic vesicle, Secretory vesicle membrane, Golgi apparatus, Trans-Golgi network membrane, Late endosome membrane, Lysosome membrane, Endoplasmic reticulum membrane, Cytoplasmic vesicle, Phagosome membrane, Synapse, Synaptosome
In immature neurons expression is localized in vesicular structures in axons and dendrites while in mature neurons it is localized to the somatodendritic region. Colocalizes with LAMP1 in kidney cells. Localization to the endoplasmic reticulum membrane was observed in the intestine but not in liver or kidney (By similarity).
Detected in all tissues tested.