Figure 5.

α-Dystrobrevins in skeletal muscle from wild-type, mdx, utrn−/−, and mdx:utrn−/− mice. (A) Sections of gastrocnemius muscle lacking NMJs from wild-type and genetically altered mice were stained with antibody to α-dystrobrevin-2 (αDB2). Staining in wild-type (a) and utrn−/− muscle (b) were indistinguishable. In mdx (c) and mdx:utrn−/− (d) muscles, the sarcolemmal staining of most fibers was greatly diminished. (B) Sections of gastrocnemius muscle containing NMJs were double labeled with α-bungarotoxin (α-BgTx) (primed letters) and antibodies to α-dystrobrevin-2 (a, c, e, g) or α-dystrobrevin-1 (b, d, f, h). Staining for α-dystrobrevin-2 in the synaptic and perisynaptic membrane was essentially unaffected by the absence of utrophin (utrn−/−), dystrophin (mdx), or both proteins (mdx:utrn−/−). Stain-ing for α-dystrobrevin-1 was strong at synapses in wild-type (wt), utrn−/−, and mdx muscle, but was lost in the double mutant. Bars: (c and h′) 40 μm.