Small G proteins of the RAB family 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) and GTPase-activating proteins (GAPs). TBC1D10B functions as a GAP for several proteins of the Rab family.

The TBC domain is predicted to function as a RabGAP, and the DAYF motif is predicted to interact with PDZ domains. TBC1D10B shares highest sequence similarity with EPI64 (TBC1D10A). The TBC domains of TBC1D10B and TBC1D10A are 81% identical, and both contain a highly conserved catalytic arginine. Fluorescence-tagged TBC1D10B localized to the plasma membrane of transfected mouse melanoma cells.