InterPro domain: IPR004140

The Exo70 protein forms one subunit of the exocyst complex (consist of Sec3, Sec5, Sec6, Sec8, Sec10, Sec15, Exo70, and Exo84 in budding yeast). First discovered in Saccharomyces cerevisiae [ 1 ], Exo70 and other exocyst proteins have been observed in several other eukaryotes, including humans. In S. cerevisiae, the exocyst complex is involved in the late stages of exocytosis, and is localised at the tip of the bud, the major site of exocytosis in yeast [ 2 ]. Exo70 interacts with the Rho3 GTPase [ 2 ]. This interaction mediates one of the three known functions of Rho3 in cell polarity: vesicle docking and fusion with the plasma membrane (the other two functions are regulation of actin polarity and transport of exocytic vesicles from the mother cell to the bud) [ 3 ]. In humans, the functions of Exo70 and the exocyst complex are less well characterised: Exo70 is expressed in several tissues and is thought to also be involved in exocytosis [ 4 ].

1. The Exocyst is a multiprotein complex required for exocytosis in Saccharomyces cerevisiae. EMBO J. 15, 6483-94
2. Rho3 of Saccharomyces cerevisiae, which regulates the actin cytoskeleton and exocytosis, is a GTPase which interacts with Myo2 and Exo70. Mol. Cell. Biol. 19, 3580-7
3. The Rho GTPase Rho3 has a direct role in exocytosis that is distinct from its role in actin polarity. Mol. Biol. Cell 10, 4121-33
4. Subunit structure of the mammalian exocyst complex. Proc. Natl. Acad. Sci. U.S.A. 94, 14438-43