Utmost cytoplasmic location of catalytic center in Na,K-motive ATPase disfavors Mitchell's phosphate-cation symport mechanism of Na/K transport across plasma membrane.
A combined electron microscopic and graded tryptic dissection analysis of the catalytic protein of pure Na,K-motive ATPase reveals that the aspartyl phosphate residue-carrying catalytic center is located at the utmost radius of the hydrophilic cytoplasmic domain. This makes the cation-phosphate symport mechanism of Na/K transport across plasma membrane as proposed by Mitchell topologically unrealistic, and indirectly favors the mechanism of conformational coupling between the catalytic and ionophoric function of the transport system.
D000818:Animals; D002384:Catalysis; D002412:Cations / Q000378:metabolism*; D002462:Cell Membrane / Q000201:enzymology*; D003593:Cytoplasm / Q000201:enzymology*; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods; D006868:Hydrolysis; D010710:Phosphates / Q000378:metabolism*; D010766:Phosphorylation; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D013552:Swine; D014462:Ultrafiltration
D002412:Cations; D010710:Phosphates; D000254:Sodium-Potassium-Exchanging ATPase