EXPRESSION ANALYSIS OF THE ATAXIN-1 PROTEIN IN TISSUES FROM NORMAL AND SPINOCEREBELLAR ATAXIA TYPE-1 INDIVIDUALS

Spinocerebellar ataxia type 1 (SCA1) is an autosomal dominant neurodeg enerative disorder caused by expansion of a CAG trinucleotide repeat w hich codes for glutamine in the protein ataxin-1. We have investigated the effect of this expansion on ataxin-1 by immunoblot analysis. The wild-type protein is detected in both normal and affected individuals; however, a mutant protein which varies in its migration properties ac cording to the size of the CAG repeat is detected in cultured cells an d tissues from SCA1 individuals. The protein has a nuclear localizatio n in ail normal and SCA1 brain regions examined but a cytoplasmic loca lization of ataxin-1 was also observed in cerebellar Purkinje cells. O ur data show that in SCAI, the expanded alleles are faithfully transla ted into proteins of apparently normal stability and distribution.