Small G proteins of the RAB family (see MIM 179508) function in intracellular vesicle trafficking by switching from the GTP-bound state to the GDP-bound state with the assistance of guanine nucleotide exchange factors (GEFs; see MIM 609700) and GTPase-activating proteins (GAPs). TBC1D10B functions as a GAP for several proteins of the Rab family (Ishibashi et al., 2009 [PubMed 19077034]).[supplied by OMIM, Nov 2010].