Since the dominant cataract mutation Cat3 was mapped very closely to the murine nuclear receptor TR2-11 gene locus, the corresponding coding region was amplified by PCR using either genomic DNA or eye-derived cDNA of wild-type (C3Hx102)F1 and of homozygous Cat3 cataract animals. The analysis of the complete coding sequences showed no differences. Additionally, the expression level was very similar. Therefore, Tr2-11 was excluded as a candidate for the Cat3 mutation. Surprisingly, the obtained sequences exhibited significant alterations to the murine Tr2-11 sequence reported previously (Lee et al., Genomics 30, 1995, 46-52). The differences in the DNA sequence predict remarkable secondary and tertiary structure alterations of the corresponding protein. The structure model of the new Tr2-11 protein is very similar to related receptors.