Isolation of a major protein component of Rosenthal fibers

Rosenthal fibers (RFs) are inclusions within astrocytes, characteristic of Alexander's disease, but also seen in astrocytic tumors and occasionally in glial scar tissue. They are granular deposits, intimately associated with intermediate filaments. Their composition has been unknown. The authors have isolated a protein of about 19 kd from partially purified RFs from Alexander's disease central nervous system tissue. Antibodies were raised to this protein and shown to react with it on nitrocellulose blots and to bind to RFs in tissue sections. Small amounts of this protein were detected in normal brain and in cultured rat astrocytes. Charge heterogeneity was inferred because several species were separated by isoelectric focusing.