<p>ATPases (or ATP synthases) are membrane-bound enzyme complexes/ion transporters that combine ATP synthesis and/or hydrolysis with the transport of protons across a membrane. ATPases can harness 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. Some ATPases work in reverse, using the energy from the hydrolysis of ATP to create a proton gradient. There are different types of ATPases, which can differ in function (ATP synthesis and/or hydrolysis), structure (e.g., F-, V- and A-ATPases, which contain rotary motors) and in the type of ions they transport [<cite idref="PUB00020603"/>, <cite idref="PUB00020604"/>]. The different types include:</p><p> <ul><li>F-ATPases (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).</li><li>V-ATPases (V1V0-ATPases), which are primarily found in eukaryotic vacuoles and catalyse ATP hydrolysis to transport solutes and lower pH in organelles.</li><li>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).</li><li>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.</li><li>E-ATPases, which are cell-surface enzymes that hydrolyse a range of NTPs, including extracellular ATP.</li> </ul> </p><p>P-ATPases (sometime known as E1-E2 ATPases) (<db_xref db="EC" dbkey="3.6.3.-"/>) are found in bacteria and in a number of eukaryotic plasma membranes and organelles [<cite idref="PUB00009616"/>]. 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, each of which transports a specific type 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.</p><p>These sequences describe the P-type ATPase primarily responsible for translocating cadmium ions (and other closely-related divalent heavy metals such as cobalt, mercury, lead and zinc) across biological membranes. These transporters are found in prokaryotes and plants. Experimentally characterised members include <db_xref db="SWISSPROT" dbkey="P37617"/> from <taxon tax_id="562">Escherichia coli</taxon>, <db_xref db="SWISSPROT" dbkey="Q10866"/> from <taxon tax_id="1773">Mycobacterium tuberculosis</taxon> and <db_xref db="SWISSPROT" dbkey="Q59998"/> from Synechocystis PCC6803. The cadmium P-type ATPases have been characterised as Type IB based on a phylogenetic analysis which combines the copper-translocating ATPases with the cadmium-translocating species [<cite idref="PUB00009616"/>]. This family and that describing the copper-ATPases (<db_xref db="INTERPRO" dbkey="IPR006403"/>) are well separated, and thus the copper-ATPases can be typed as IB1 and the cadmium-ATPases as IB2. </p><p>More information about this protein can be found at Protein of the Month: ATP Synthases [<cite idref="PUB00020719"/>].</p> ATPase, P-type, heavy metal-(Cd/Co/Hg/Pb/Zn)-translocating