P-type ATPase, B chain, subfamily IA (IPR006391)

Short name: P-type_ATPase_bsu_IA

Overlapping homologous superfamilies

Family relationships

  • P-type ATPase (IPR001757)
    • P-type ATPase, B chain, subfamily IA (IPR006391)


Transmembrane ATPases are membrane-bound enzyme complexes/ion transporters that use ATP hydrolysis to drive the transport of protons across a membrane. Some transmembrane ATPases also work in reverse, harnessing the energy from a proton gradient, using the flux of ions across the membrane via the ATPase proton channel to drive the synthesis of ATP.

There are several different types of transmembrane ATPases, which can differ in function (ATP hydrolysis and/or synthesis), structure (e.g., F-, V- and A-ATPases, which contain rotary motors) and in the type of ions they transport [PMID: 15473999, PMID: 15078220]. The different types include:

  • F-ATPases (ATP synthases, F1F0-ATPases), which are found in mitochondria, chloroplasts and bacterial plasma membranes where they are the prime producers of ATP, using the proton gradient generated by oxidative phosphorylation (mitochondria) or photosynthesis (chloroplasts).
  • V-ATPases (V1V0-ATPases), which are primarily found in eukaryotes and they function as proton pumps that acidify intracellular compartments and, in some cases, transport protons across the plasma membrane [PMID: 20450191]. They are also found in bacteria [PMID: 9741106].
  • A-ATPases (A1A0-ATPases), which are found in Archaea and function like F-ATPases, though with respect to their structure and some inhibitor responses, A-ATPases are more closely related to the V-ATPases [PMID: 18937357, PMID: 1385979].
  • P-ATPases (E1E2-ATPases), which are found in bacteria and in eukaryotic plasma membranes and organelles, and function to transport a variety of different ions across membranes.
  • E-ATPases, which are cell-surface enzymes that hydrolyse a range of NTPs, including extracellular ATP.

P-ATPases (also known as E1-E2 ATPases) (EC:3.6.3.-) are found in bacteria and in a number of eukaryotic plasma membranes and organelles [PMID: 9419228]. P-ATPases function to transport a variety of different compounds, including ions and phospholipids, across a membrane using ATP hydrolysis for energy. There are many different classes of P-ATPases, which transport specific types of ion: H+, Na+, K+, Mg2+, Ca2+, Ag+ and Ag2+, Zn2+, Co2+, Pb2+, Ni2+, Cd2+, Cu+ and Cu2+. P-ATPases can be composed of one or two polypeptides, and can usually assume two main conformations called E1 and E2.

These sequences describe the P-type ATPase subunit of the complex responsible for translocating potassium ions across biological membranes in microbes. In Escherichia coli and other species, this complex consists of the proteins KdpA, KdpB, KdpC and KdpF. KdpB is the ATPase subunit, while KdpA is the potassium-ion translocating subunit [PMID: 1970651]. The function of KdpC is unclear, although it has been suggested to couple the ATPase subunit to the ion-translocating subunit [PMID: 9858692], while KdpF serves to stabilise the complex [PMID: 10608856]. The potassium P-type ATPases have been characterised as Type IA based on a phylogenetic analysis which places this clade closest to the heavy-metal translocating ATPases (Type IB) [PMID: 9419228]. Others place this clade closer to the Na+/K+ antiporter type (Type IIC) based on physical characteristics [PMID: 1970651].

GO terms

Biological Process

GO:0006813 potassium ion transport

Molecular Function

GO:0005524 ATP binding
GO:0008556 potassium-transporting ATPase activity

Cellular Component

GO:0016021 integral component of membrane

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.