Rab proteins recruit specific sets of effector proteins onto membranes in their GTP-bound state and coordinate consecutive stages of transport, such as vesicle formation, vesicle and organelle motility, and tethering of vesicles with target membranes [53, 55].The significance of the role that these members of the claudin and the RAS superfamily of small GTPases might play in sheep susceptibility to coccidiosis is outlined below. This evidence concerns the gene AGFG1 and coccidiosis.