The objectives are to define the ultrastructural cytologic distribution of (Na+ + K+)ATPase in the mouse nervous system and developmental changes in this distribution in cerebellum, optic nerve, and in tissue culture. This will lead to understanding cell membrane differentiation related to cation transport function in the brain. Mouse brain (Na+ + K+)-ATPase will be purified by detergent extraction and isopycnic sedimentation. The catalytic polypeptide will be identified by Na+-dependent phosphorylation and separated by polyacrylamide gel elebrophoresis. Specific antisera to the holoenzyme and catalytic unit will be raised in rabbits. Immunocytochemical studies of mouse nervous system will be performed with tissue specific antibodies at the light and electron microscopy levels by means of peroxidase-antiperoxidase and protein A-gold methods. Antibodies will be purified by immunoafinity chromatography with purified catalysic polypeptide. This project involves disciplines of brain anatomy, ontogeny, biochemistry, immunology, and neurocellular biology.