Fig. 3. Phospholemman immunoreactivity in cerebellar cortex, choroid plexus, and ventricular wall. A–C, Cerebellar cortex double-labeled for phospholemman (green), the α1 subunit of Na,K-ATPase (red), and the combined images. ml, Molecular layer; gl, granular layer. Immunoreactivity for α1 in the glomeruli (g) in the granular layer was particularly bright and the granule cell bodies (gc) were also stained, as was the molecular layer. Antibody to phospholemman stained the molecular layer and ring-stained Purkinje cells (pc) and axons in the granular layer. D–F, Same structures double-labeled for the α2 isoform (red) and phospholemman (green). Purkinje cells occasionally stained for α2, as reported previously (Peng et al., 1997); astrocytes in the granular layer (astr) were stained prominently for α2 but very lightly for phospholemman. G–I, Section of rat brain more lateral than that of Figure 2 double-labeled for Na,K-ATPase α1 (red) and phospholemman (green). Both proteins were confined to the apical surface of the polarized epithelium of the choroid plexus (CP), which lies here in a narrow ventricular space ventral to the chamber seen in Figure 2. On the rostral surface of the ventricle, a cuboidal epithelium of ependymal cells, presumed tanycytes (e), is seen that was prominently stained for both Na,K-ATPase and phospholemman at its apical surface.