PHOSPHORYLATION OF ALPHA-CRYSTALLIN-B IN ALEXANDERS DISEASE BRAIN

The phosphorylation of alpha-crystallin B was studied in homogenates of autopsy samples of brain tissue from patients with Alexander's disease, a condition characterized by over-expression of this protein. After incubation in the presence of [gamma-P-32]ATP and cAMP the homogenates were analyzed by two-dimensional electrophoresis, (isoelectric focusing followed by SDS-PAGE). Three major polypeptides having the same molecular weight as bovine lens alpha-crystallin B and pIs 7.1, 6.9 and 6.7 were detected in the Coomassie blue stained gels. These three polypeptides were recognized by an alpha-crystallin B-specific antiserum in Western blots. The polypeptides with pIs 7.1 and 6.7 co-migrated in isoelectric focusing gels with bovine lens alpha-B and its phosphorylated form alpha-Bp, respectively. Radioautography of the two-dimensional gels demonstrated the presence of P-32 in the most acidic polypeptide. The results demonstrate the occurrence of alpha-B phosphorylation in Alexander's disease brain tissue.