P-type ATPases
p-type atpases
The P-type ATPases, also known as E1-E2 ATPases, are a large group of evolutionarily related ion and lipid pumps that are found in bacteria, archaea, and eukaryotes. They are alpha-helical bundle primary transporters referred to as P-type ATPases because they catalyze auto- (or self-) phosphorylation of a key conserved aspartate residue within the pump. In addition, they all appear to interconvert between at least two different conformations, denoted by E1 and E2.  Most members of this transporter family are specific for the pumping of a large array of cations, however one subfamily is involved in flipping phospholipids to maintain the asymmetric nature of the biomembrane.  Prominent examples of P-type ATPases are the sodium-potassium pump (Na +,K +-ATPase), the plasma membrane proton pump (H +-ATPase), the proton-potassium pump (H +,K +-ATPase), and the calcium pump (Ca 2+ -ATPase).