Figure 1.

Identification and phenotype of qv^3J mice. A, Schematic of WT, qv^3J, and qv^4J mutant βIV spectrin. B, PCR-based screening for qv^3J homozygous mutant mice using the StyI restriction enzyme. C, Double immunostaining of rat sciatic nerve with antibodies against Nav channels (Pan Nav) or the SD domain of βIV spectrin (βIV SD) shows that the βIV SD epitope is absent in qv^3J mice. D, E, qv^3J mice clasp their hindlegs together and have significant gait abnormalities, including weakness, tremor, and a dragging of their hindlegs. F, Immunoblot analysis for a variety of proteins associated with myelinated axons, including Nav channels (Pan Nav, Nav1.2), Caspr, Kv1.2, CNP, MBP, β-actin, α-tubulin, and SD-containing βIV spectrin isoforms. Scale bars, 5 μm.