PKL

PKL collects the phosphoinositide phosphate kinases that build PI(4,5)P2: the type I enzymes PIP5K1A, PIP5K1B and PIP5K1C phosphorylate PI4P at position 5, while the type II enzymes PIP4K2A, PIP4K2B and PIP4K2C phosphorylate PI5P at position 4, so two structurally distinct routes converge on the same product. PIP5K1C is enriched at focal adhesions, where it regulates talin and vinculin-dependent adhesion, and type I kinases supply substrate lipid for phospholipase C, ion channels, actin-binding proteins and clathrin-coated vesicle formation. PIP4K2C modulates mTORC2-dependent signaling and insulin responses in muscle. PIP5K3 is a less-characterized relative. The family shows how one minor phospholipid can be made by unrelated enzymes.