Class III PI 3-kinase is a subgroup of the enzyme family, phosphoinositide 3-kinase that share a common protein domain structure, substrate specificity and method of activation.
There is only one known class III PI 3-kinase, Vps34, which is also the only PI 3-kinase expressed in all eukaryotic cells. In humans it is encoded by the PIK3C3 gene. In human cells Vps34 associates with a regulatory subunit, PIK3R4(p150, Vps15).[1]