抄録
The proteins which compose the complex of dystrophin and its associated proteins were analyzed by two-dimensional PAGE, i.e., electrofocusing in the presence of 8M urea followed by SDS PAGE. Silver-staining of the gel showed many more spots than were expected from the results of one-dimensional SDS PAGE. By examination of their reactivity with specific antibodies, various lectins and 3-(trifluoromethyl)-3-(m-[125I] iodophenyl)-diazirine, most of these spots were identified as dystrophin and its associated proteins described previously. Several as yet unidentified minor proteins were also detected. Dystrophin-associated protein Al was separated into two groups, α-A 1 and β-A 1, both composed of numerous spots. These groups differed from each other in isoelectric point, molecular mass, and reactivity with antibodies. The β-A 1 group (64 kDa) was more basic than the α-A 1 group (60 kDa). Beta-A 1 but not α-A 1 reacted with several lectins, indicating that β-A 1 is a glycoprotein. This is incompatible with the report that 59DAG, which corresponds to A 1 (α-A 1+β-A 1), is not a glycoprotein [Ervasti et al. (1991) Cell 66, 1121-1131]. The charge heterogeneity observed in α-A 1 and β-A 1 may be partially due to differential phosphorylation. The charge heterogeneity of A2 and A3a may, at least to some extent, be due to differential sialilation of their carbohydrates.
