Ras suurperekonda kuuluvad monomeersed GTPaasid, mis on raku plasma- ja organellide membraanis seotud GTP-ga, The Rab family of proteins is a member of the Ras superfamily of monomeric G proteins.Rab GTPases regulate many steps of membrane traffic, including vesicle formation, vesicle movement along actin and tubulin networks, and membrane fusion.