CK2α is concentrated in CNS and PNS nodes of Ranvier. (A and B) CK2α immunoreactivity is visible as numerous punctiform structures (B1 and B3, arrows) colabeled for ankyrin G (B2 and B3, arrows) within the alveus and cortical white matter that probably correspond to nodes. B1–B3 are enlarged views of the boxed areas in A1–A3. (C and D) Ranvier nodes are labeled for CK2α and ankyrin G (C1–C3, arrowheads) in teased fibers of the sciatic nerve. CK2α labeling is concentrated at the membrane of the nodal region (D1, arrows). CK2α immunoreactivity is also visible in the nucleus of a Schwann cell (e.g., C1 and C3, arrows). al, alveus; wm, white matter. Bars: (A) 26.8 μm; (B) 6. 71 μm; (C) 23.2 μm; (D) 3 μm.