The Role of Phospholipids in Na-K ATPase
It has been known for a long time that lipids present in the plasma membrane influence the activity of the Na-K ATPase system. Treatment of Na-K ATPase preparations with detergents, phospholipases and organic solvents leads to partial or complete inactivation of the enzyme activity (for a recent review see Kimelberg, 1976). Moreover Arrhenius plots for the Na-K ATPase activity show a marked discontinuity around 20°C, which is generally attributed to a change in the solid/fluid transition of the fatty acid chains of the phospholipids. This interpretation has received support from studies of electron paramagnetic resonance spectra with spinlabeled fatty acids (Grisham and Barnett, 1973) and of fluorescent probe studies (Charnock and Bashford, 1975). Two questions remain: what is the molecular mechanism of this phospholipid effect, and is the interaction due to specific phospholipids?
KeywordsElectron Paramagnetic Resonance Spectrum Fatty Acid Chain Control Preparation Individual Phospholipid Acidic Phospholipid
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