EXPRESSION OF DYSTROPHIN-ASSOCIATED PROTEIN 35DAG (A4) AND 50DAG (A2)IS CONFINED TO STRIATED MUSCLES

A monoclonal antibody MA4-2 against a dystrophin-associated protein 35 DAG (A4) was established and applied to examine the distribution of 35 DAG in monkey tissue and its expression in DMD patients. In immunoblot ting after two-dimensional gel electrophoresis of crude skeletal muscl e extracts, MA4-2 reacted exclusively with an apparent single spot loc ated in a similar position to rabbit 35DAG in each animal examined. 35 DAG was detected only in striated muscles (quadriceps femoris and card iac muscles), but not in other tissues examined, including smooth musc le (aorta, uterus), brain, nerve, lung, and liver. This distribution p attern is the same as that of 50DAG but different from that of 43DAG ( A3a) [Mizuno et al. (1993) J. Biochem. 114,936-941]. In Duchenne muscu lar dystrophy muscles, 35DAG was distinctly present, but greatly reduc ed in amount. This is also the case with 50DAG. On the basis of these results, it is concluded that 35DAG and 50DAG are striated muscle-spec ific and may be important in the pathogenesis of Duchenne muscular dys trophy.