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.
KeywordsHuman Lymphocyte Allosteric Modulation Adenosine Triphosphatase Artificial Membrane Terminal Phosphate
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