Acts as a GTPase activating protein for RAB5. Does not act on RAB4 or RAB11 (By similarity). TBC1 domain family member 3B TBC1D3B MDVVEVAGSWWAQEREDIIMKYEKGHRAGLPEDKGPKPFRSYNNNVDHLGIVHETELPPLTAREAKQIRREISRKSKWVDMLGDWEKYKSSRKLIDRAYKGMPMNIRGPMWSVLLNIEEMKLKNPGRYQIMKEKGKRSSEHIQRIDRDISGTLRKHMFFRDRYGTKQRELLHILLAYEEYNPEVGYCRDLSHIAALFLLYFPEEDAFWALVQLLASERHSLQGFHSPNGGTVQGLQDQQEHVVATSQSKTMGHQDKKDLCGQCSPLGCLIRILIDGISLGLTLRLWDVYLVEGEQALMPITRIAFKVQQKRLTKTSRCGPWARFCNRFVDTWARDEDTVLKHLRASMKKLTRKQGDLPPPAKPEQGSSASRPVPASRGGKTLCKGDRQAPPGPPARFPRPIWSASPPRAPRSSTPCPGGAVREDTYPVGTQGVPSPALAQGGPQGSWRFLQWNSMPRLPTDLDVEGPWFRHYDFRQSCWVRAISQEDQLAPCWQAEHPAERVRSAFAAPSTDSDQGTPFRARDEQQYAPTSGPCLCGLHLESSQFPPGF TBC3B_HUMAN 549 TBC1D3I