Small GTPase which cycles between active GTP-bound and inactive GDP-bound states. In its active state, binds to a variety of effector proteins to regulate homeostasis of late endocytic pathway, including endosomal positioning, maturation and secretion . Plays a role in cytotoxic granule exocytosis in lymphocytes. Required for both granule maturation and granule docking and priming at the immunologic synapse.
Subcellular locations: Membrane, Melanosome, Late endosome, Lysosome
Identified by mass spectrometry in melanosome fractions from stage I to stage IV (, ). Localizes to endosomal exocytic vesicles .
Found in all the examined tissues except in brain. Low expression was found in thymus, kidney, muscle and placenta. Detected in melanocytes, and in most tumor cell lines examined. Expressed in cytotoxic T-lymphocytes (CTL) and mast cells.