E1–E2-type ATPase

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A superfamily of ion-pumping ATPases (P-type ATPases), present in prokaryotes and eukaryotes, that can be divided into four main groups: 1. calcium-transporting ATPases (e.g. of sarcoplasmic reticulum), 2. sodium-potassium ATPases of plasma membrane and hydrogen-potassium ATPase of gastric mucosa, 3. plasma membrane proton pumps of plants, fungi, and lower eukaryotes and 4. all bacterial P-type ATPases, except the magnesium ATPase of Salmonella typhimurium. The catalytic (α) subunit or region generally has multiple membrane-spanning domains and the second (β) subunit is involved in stabilizing and transporting the α subunit to the membrane. The pumps are generally inhibited by ATP analogues such as vanadate, but selectively by other inhibitors (e.g. ouabain for the sodium-potassium ATPase, thapsigargin for the calcium ATPase). A general feature is that an aspartyl-phosphoryl enzyme intermediate is formed during the catalytic cycle. Compare V-type ATPase

Subjects: Medicine and Health.

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