Vac14 is a scaffold for the Fab1 kinase complex, a complex that allows for the dynamic interconversion of PI3P and PI(3,5)P2p (phosphoinositide phosphate (PIP) lipids, that are generated transiently on the cytoplasmic face of selected intracellular membranes). This interconversion is regulated by at least five proteins in yeast: the lipid kinase Fab1p, lipid phosphatase Fig4p, the Fab1p activator Vac7p, the Fab1p inhibitor Atg18p, and Vac14p, a protein required for the activity of both Fab1p and Fig4p. This domain appears to be the one responsible for binding to Fab1. The full length Vac14 in yeasts is likely to be a protein carrying a succession of HEAT repeats, most of which have now degenerated. This regulatory system is crucial for the proper functioning of the mammalian nervous system.

1: VAC14 nucleates a protein complex essential for the acute interconversion of PI3P and PI(3,5)P(2) in yeast and mouse. Jin N, Chow CY, Liu L, Zolov SN, Bronson R, Davisson M, Petersen JL, Zhang Y, Park S, Duex JE, Goldowitz D, Meisler MH, Weisman LS; EMBO J. 2008;27:3221-3234. PMID:19037259