Pathways & interactions
K+ transporting P-type ATPase, F subunit (IPR011726)
Short name: KdpF
Overlapping homologous superfamilies
This entry represents the F subunit (KdpF) of a P-type K+ translocating ATPase (Kdp) in archaea and bacteria. KdpF is a very small integral membrane peptide. The kdpABC operon of Escherichia coli codes for the high affinity K+ translocating Kdp complex [PMID: 9789555, PMID: 10608856]. KdpF is found upstream of the KdpA subunit (IPR004623). Because of its very small size and highly hydrophobic character, it is sometimes missed in genome annotation.Though KdpF is not essential in vivo [PMID: 9789555] it is part of the complex and functions as a stabilising element in vitro [PMID: 10608856].
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.