BETA-DYSTROGLYCAN - SUBCELLULAR-LOCALIZATION IN RAT-BRAIN AND DETECTION OF A NOVEL IMMUNOLOGICALLY RELATED, POSTSYNAPTIC DENSITY-ENRICHED PROTEIN

The distribution of a glycoprotein component of the muscle dystrophin complex, beta-dystroglycan, has been determined in subcellular fractio ns of adult rat forebrain. The results show that beta-dystroglycan is enriched in several membrane fractions, including synaptic membranes, but in marked contrast to dystrophin is not detectable in the postsyna ptic density fraction. The antiserum also recognises a second molecula r species of apparent molecular mass of 164 kDa which is highly enrich ed in the postsynaptic density fraction. Preabsorption of the antiseru m with the antigen (a 22-mer peptide corresponding to the C-terminal s equence of rabbit skeletal muscle beta-dystroglycan) abolished reactiv ity against both beta-dystroglycan and the 164-kDa postsynaptic densit y-enriched protein, confirming that the two species are immunologicall y related. Enzymatic removal of N-linked oligosaccharide lowered the a pparent molecular mass of beta-dystroglycan by 3 kDa but did not alter the mass of the 164-kDa species.