Figure 8. Compensatory changes by 4.1 proteins in the mutant nerves.

Teased nerve fibers from wild type and 4.1B^−/− sciatic nerves were immunostained and blotted with a panel of antibodies to 4.1B, 4.1R and 4.1G. A. Staining with the 4.1B (HP) antibody demonstrates high-level expression along the axonal membrane, which is lost in the 4.1B^−/− sciatic nerves (the nerve fibers in the right panel are not visible on comparable exposure). On prolonged exposures (5X) of the mutant nerves (inset, right panel), persistent 4.1B staining is evident in the incisures, several of which are highlighted with arrowheads. B. 4.1R staining is undetected in wild type nerves but modestly increased in the paranodes of the 4.1B^−/− nerves; nodes are indicated by white arrowheads. The inset (right panel) shows staining of 4.1R overlaps substantially with that of Caspr in the paranodes. C. Nerves from the knockout mice exhibit increased numbers of incisures for fibers of the same diameter. In addition, staining for 4.1G appears increased in individual clefts. D. Caspr staining persists in the paranodes of the double 4.1B^−/− 4.1R^−/− sciatic nerves nerves. E. Blotting analysis of 4.1 proteins in wt vs. 4.1B^−/− sciatic nerves is shown; antibodies used were generated against the head piece (HP) of 4.1B, exon 19 of 4.1R, the U3 domain of 4.1G, and the HP of 4.1N (see Kang et al., 2009 for details). All scale bars, 10 μm.