(Na+ + K+)-adenosinetriphosphatase in the brain of Shiverer (Shi/Shi) mice.

The myelin-deficient Shiverer (Shi/Shi) mutant mouse may be a useful model in assessing the dependence of brain (Na+ + K+)-ATPase concentration and composition on myelin membrane formation. Brain microsomal membranes from age-matched control (+/+) and Shiverer (Shi/Shi) mice were fractionated by differential centrifugation and sucrose gradient sedimentation. No reduction in (Na+ + K+)-ATPase specific activity was measured in whole homogenates, high- and low-speed fractions or gradient fractions from brains of Shi/Shi mice as compared to those of +/+ mice. In addition, sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting with antisera specific for mouse brain (Na+ + K+)-ATPase revealed no significant difference in catalytic subunit composition between fractions of +/+ and Shi/Shi brains. The similar results obtained for both +/+ and myelin-deficient Shi/Shi mice suggest that myelin contributes little to total brain (Na+ + K+)-ATPase.