Phosphatidylinositol as the endogenous activator of the (Na+ + K+)-ATPase in microsomes of rabbit kidney.
Incubation of rabbit kidney microsomes with pig pancreatic phospholipase A2 produced residual membrane preparations with very low (Na+ + K+)-ATPase activity. The activity could be restored by recombination with lipid vesicles of negatively-charged glycerophospholipids. Vesicles of pure phosphatidylcholine and phosphatidylethanolamine were virtually inactive in this respect, but could reactivate in the presence of cholate. Incubation of the microsomes with a combination of phospholipase C (Bacillus cereus) and spingomyelinase C (Staphylococcus aureus) resulted in 90--95% release of the phospholipids. The residual membrane contained only phosphatidylinositol and still showed 50--100% of the (Na+ + K+)-ATPase activity.
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D004789:Enzyme Activation; D007668:Kidney / Q000032:analysis / Q000201:enzymology*; D008566:Membranes / Q000032:analysis; D008861:Microsomes / Q000201:enzymology; D010716:Phosphatidylinositols / Q000494:pharmacology*; D010740:Phospholipases; D010743:Phospholipids / Q000032:analysis; D011188:Potassium / Q000378:metabolism; D011817:Rabbits; D012964:Sodium / Q000378:metabolism; D013108:Sphingomyelin Phosphodiesterase
D010716:Phosphatidylinositols; D010743:Phospholipids; D012964:Sodium; D010740:Phospholipases; D013108:Sphingomyelin Phosphodiesterase; D000251:Adenosine Triphosphatases; D011188:Potassium