Possesses GTPase activator activity towards RAB32, RAB33B and RAB38 (, ). Regulates the trafficking of melanogenic enzymes TYR, TYRP1 and DCT/TYRP2 to melanosomes in melanocytes by inactivating RAB32 and RAB38. Inhibits RAB32 and RAB38 activation both directly by promoting their GTPase activity and indirectly by disrupting the RAB9A-HPS4 interaction which is required for RAB32/38 activation .
Subcellular locations: Cytoplasm, Melanosome
Melanosomal localization is mediated by RAB9A.
Widely expressed.