DISSOCIATION OF THE COMPLEX OF DYSTROPHIN AND ITS ASSOCIATED PROTEINSINTO SEVERAL UNIQUE GROUPS BY N-OCTYL BETA-D-GLUCOSIDE

Dystrophin is purified as a complex with several proteins from the dig itonin-solubilized muscle cell membrane. Most of dystrophin-associated proteins (DAPs) are assumed to form a large oligomeric transmembranou s glycoprotein complex on the sarcolemma and link dystrophin with a ba sement membrane protein, laminin. In the present study, we found that the purified dystrophin-DAP complex was dissociated into several group s by n-octyl-beta-D-glucoside treatment. In particular, we found that the glycoprotein complex stated above was dissociated into two distinc t groups: one composed of 156DAG and 43DAG (A3a) and the other compose d of SODAG, 35DAG and A3b. We confirmed by crosslinking and immunoaffi nity chromatography that these two groups existed in a complexes. We t hus concluded that the glycoprotein complex consists of these two subc omplexes. Furthermore, A3b and 43DAG, which had been formerly treated simply as the 43DAG doublets due to their similar electrophoretic mobi lities in SDS/PAGE, were shown to be present in two different subcompl exes. Based on the analyses by two-dimensional gel electrophoresis, pe ptide mapping and immunoblotting, we concluded that A3b is a novel DAP different from 43DAG.