proton pump n a molecular mechanism that transports hydrogen ions across cell membranes
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the enzyme in the oxyntic cells of the stomach that causes acid secretion by producing hydrogen ions in exchange for potassium ions.
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a system for transporting protons (hydrogen ions) across cell membranes, often exchanging them for other positively charged ions; it may be driven by energy supplied by ATP metabolism, light, or a flow of electrons. See also H+,K+-ATPase. Called also hydrogen p.Medical dictionary. 2011.