Two-sided bi-directional Na+/K+- ATPase-liposomes. Structure and function
The minimal functional unit of the Na+/K+-ATPase or sodium pump system, which contains also a hormonal and pharmacological receptor, is composed of a 110 kD α-subunit, a β-glycoprotein, membrane phospholipids and cholesterol; its primary function consists, in mediating the transmembrane movements of Na and K ions with energy derived from ATP hydrolysis (13,14). It is well known that the link between the chemical reaction and the vectorial process is made in a first step by transfer of the terminal phosphate of the ATP molecule to an aspartyl residue located on the intracellular protein loops of the a subunit and that, secondly; the phosphorylation of the pump induces a conformational change priming the transmembrane Na/K-exchange. However, the molecular mechanism of the vectorial ion movement, in particular its allosteric modulation by the receptor for cardioactive steroids is still poorly understood.
KeywordsCholesterol Hydrolysis EDTA Citrate Adenosine
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