ATP-dependent membrane-bound cation and aminophospholipid transporters
The P-type ATPases, are a large family of integral membrane transporters that are of critical importance in all kingdoms of life. They generate and maintain (electro-) chemical gradients across cellular membranes, by translocating cations, heavy metals and lipids. They are distinguished from other main classes of transport ATPases (F- , V- , and ABC- type) by the formation of a phosphorylated (P-) intermediate state in the catalytic cycle. A general characteristic of P-type ATPases is a bundle of transmembrane helices which make up the transport path, and three domains on the cytoplasmic side of the membrane. Members include pumps that transport various light metal ions, such as H(+), Na(+), K(+), Ca(2+), and Mg(2+), pumps that transport indispensable trace elements, such as Zn(2+) and Cu(2+), pumps that remove toxic heavy metal ions, such as Cd(2+), and pumps such as aminophospholipid translocases which transport phosphatidylserine and phosphatidylethanolamine.