Ultrastructural localization of adhalin in normal murine skeletal myofiber

The ultrastructural localization of adhalin and its relations to dystrophin, beta-dystroglycan, and beta-spectrin were studied in normal murine skeletal myofibers. The C-terminal peptides of adhalin and beta-dystroglycan were synthesized based on their cDNAs, and the affinity-purified antibodies against these peptides were produced. Single-immunolabeling electron microscopy showed that the adhalin was located just inside the muscle plasma membrane or inside the myofiber a short distance from the plasma membrane. The adhalin signal was also noted at the sarcoplasmic side of plasmalemmal invaginations or at vesicular structures in subsarcolemmal areas. Double-immunogold-labeling electron microscopy disclosed a similar localization of dystrophin, beta-dystroglycan, and beta-spectrin. The close association of adhalin with dystrophin or beta-dystroglycan was demonstrated by formation of doublets by signals of antibodies of adhalin with those of dystrophin or beta-dystroglycan and was confirmed by statistical analyses. This study demonstrated that the location of adhalin is close to that of dystrophin and beta-dystroglycan at the muscle plasma membrane.