FYVE domain 2 found in yeast protein VAC1 (Vac1p) and similar proteins
Vac1p, also termed vacuolar segregation protein Pep7p, or carboxypeptidase Y-deficient protein 7, or vacuolar protein sorting-associated protein 19 (Vps19p), or vacuolar protein-targeting protein 19, is a phosphatidylinositol 3-phosphate (PtdIns3P or PI3P)-binding protein that interacts with a Rab GTPase, GTP-bound form of Vps21p, and a Sec1p homologue, Vps45p, to facilitate Vps45p-dependent vesicle-mediated vacuolar protein sorting. It also acts as a novel regulator of vesicle docking and/or fusion at the endosome and functions in vesicle-mediated transport of Golgi precursor carboxypeptidase Y (CPY), protease A (PrA), protease B (PrB), but not alkaline phosphatase (ALP) from the trans-Golgi network-like compartment (TGN) to the endosome. Vac1p contains an N-terminal classical TFIIIA-like zinc finger, two putative zinc-binding FYVE fingers, and a C-terminal coiled coil region. The family corresponds to the second FYVE domain that is responsible for the ability of Pep7p to efficiently interact with Vac1p and Vps45p.