Role of sulfatide on phosphoenzyme formation and ouabain binding of the (Na+ + K+)ATPase.
A microsomal fraction rich in (Na+ + K+)ATPase activity has been isolated from the outer medulla of pig kidney. The ability of this preparation to form phosphoenzyme on incubation with [gamma-32P]ATP and to bind [3H]ouabain was studied when its sulfatide was hydrolyzed by arylsulfatase treatment. The K+-dependent hydrolysis of the Na+-dependent phosphorylated intermediate as well as the ouabain binding were inactivated in direct relation to the breakdown of sulfatide. Both characteristics of the (Na+ + K+)ATPase preparation, lost by arylsulfatase treatment, were partially restored by the sole addition of sulfatide. These experiments indicate that sulfatide may play a role in sodium ion transport either in the conformational transition of the K+-insensitive phosphointermediate, E1P, to the K+-sensitive intermediate, E2P, or in the configuration of the high-affinity binding site for K+ of the E2P form. In addition, this glycolipid may have a specific role in the proteolipidic subunit that binds ouabain.
Jedlicki
A
A
Zambrano
F
F
D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001192:Arylsulfatases / Q000494:pharmacology; D066298:In Vitro Techniques; D007679:Kidney Medulla / Q000201:enzymology; D010042:Ouabain / Q000378:metabolism*; D010766:Phosphorylation; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D013433:Sulfoglycosphingolipids / Q000378:metabolism*; D013552:Swine
D013433:Sulfoglycosphingolipids; D010042:Ouabain; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D012964:Sodium; D001192:Arylsulfatases; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium