The regulation and function of Class III PI3Ks: novel roles for Vps34

The Class III PI3K (phosphoinositide 3-kinase), Vps34 (vacuolar protein sorting 34), was first described as a component of the vacuolar sorting system in Saccharomyces cerevisiae and is the sole PI3K in yeast. The homologue in mammalian cells, hVps34, has been studied extensively in the context of endocytic sorting. However, hVps34 also plays an important role in the ability of cells to respond to changes in nutrient conditions. Recent studies have shown that mammalian hVps34 is required for the activation of the mTOR (mammalian target of rapamycin)/S6K1 (S6 kinase 1) pathway, which regulates protein synthesis in response to nutrient availability. In both yeast and mammalian cells, Class III PI3Ks are also…