[Receptor function stability of cerebral Na+,K+-ATPase under conditions of modification of their enzymatic activity]

Rat and bovine Na+, K(+)-ATP-ase and isozymes have been studied for their sensitivity to ouabain to evaluate the conformational stability of the receptor for cardioactive steroid and its interconnection with intramembrane organization of catalytic polypeptide under modification of native functional conformation of membrane-bound enzyme by treatment with agents known to affect the membrane integrity (such as SDS, heat, phospholipase A2). The higher sensitivity of alpha-isoform of Na, K-ATP-ase activity to detergent as compared to alpha + under their irreversible inactivation that is due to its preferential sollubilization from the membrane is discovered. The existence of differences between isozymes in the hydrophobic protein-lipid interaction has been supposed. The greater sensitivity of alpha-isozyme to disorganization of the enzyme native phospholipid environment with phospholipase A2 has been also established. It is shown that Na+, K(+)-ATP-ase receptor function of ouabain-sensitive and ouabain-resistant enzyme types is much more conservative in comparison with hydrolytic and resistant to possible disorders of protein-lipid interactions.