ADHALIN (ALPHA-SARCOGLYCAN) IS NOT REQUIRED FOR ANCHORING OF NITRIC-OXIDE SYNTHASE-I (NOS-I) TO THE SARCOLEMMA IN NONMAMMALIAN SKELETAL (STRIATED) MUSCLE-FIBERS

Previous studies have shown the association of NOS I with the sarcolem ma in mammalian striated muscle fibers, implicating the dystrophin com plex (DC) as a major anchor for the enzyme. The potential role of the sarcoglycan subcomplex, especially of alpha-sarcoglycan (adhalin), as part of the DC in holding of NOS I in the sarcolemmal position was exa mined by carrying out a comparative study on the distribution of NOSI, dystrophin, dystrophin-associated glycoproteins (DAG) and alpha-sarco glycan in various skeletal muscles of non-mammals. Rat muscles were in cluded since they reflect the situa tion in mammals. Catalytic NOS-ass ociated diaphorase (NOSaD) activity as well as NOS I and DAG immunorea ctivities were positive in the saracolemma region of skeletal muscle f ibers of rats, chicken, and turtles. Adhalin immunoreactivity was pres ent in the rat but absent in the chicken and turtle muscle surface mem brane. These data suggest that alpha-sarcoglycan and therefore the ent ire sarcoglycan subcomplex may not be needed for localizing NOS I to t he sarcolemma in these non-mammalian species. This may hold for skelet al musle fibers in general.