P-type ATPase

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 α-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 (Ca²⁺-ATPase).

Discovery

The first P-type ATPase discovered was the Na⁺,K⁺-ATPase, which Nobel laureate Jens Christian Skou isolated in 1957. The Na⁺,K⁺-ATPase was only the first member of a large and still-growing protein family, which in May 2013 had around 500 confirmed and unique members in Swiss-Prot (Prosite motif PS00154).

P-type

P-type may refer to:

Extrinsic semiconductor

An extrinsic is a semiconductor that has been doped, that is, into which a doping agent has been introduced, giving it different electrical properties than the intrinsic (pure) semiconductor.

Doping involves adding dopant atoms to an intrinsic semiconductor, which changes the electron and hole carrier concentrations of the semiconductor at thermal equilibrium. Dominant carrier concentrations in an extrinsic semiconductor classify it as either an n-type or p-type semiconductor. The electrical properties of extrinsic semiconductors make them essential components of many electronic devices.

Semiconductor doping

Semiconductor doping is the process that changes an intrinsic semiconductor to an extrinsic semiconductor. During doping, impurity atoms are introduced to an intrinsic semiconductor. Impurity atoms are atoms of a different element than the atoms of the intrinsic semiconductor. Impurity atoms act as either donors or acceptors to the intrinsic semiconductor, changing the electron and hole concentrations of the semiconductor. Impurity atoms are classified as donor or acceptor atoms based on the effect they have on the intrinsic semiconductor.