 This domain pair constitutes a superdomain, a heritable unit that is found in various proteins in fungi, plants and animals.In addition, phosphatidylinositol 3-kinase (PI3-kinase), an enzyme that phosphorylates phosphoinositides on the 3-hydroxyl group of the inositol ring, also uses a C2 domain to bind to the membrane (e.g.1e8w PDB entry).