A fibroblast cDNA library was screened by hybridization to a yeast artificial chromosome containing genomic sequences from human Xq28. The majority of positive cDNA clones were found to correspond to the cDNA coding for TXREB, an HTLV-1 enhancer-binding protein. Sequence analysis of the Xq28 genomic DNA revealed a number of deleterious changes compared to the previously reported cDNA. In addition, both the genomic DNA and cDNA isolates were found to be lacking a 599-bp sequence, bracketed by GT and AG, in the 5' untranslated region. These results suggest that the Xq28-linked gene is a processed pseudogene for TXREB and that the previously reported cDNA was only partially processed. Southern blot analysis on a hybrid mapping panel confirmed the presence of at least one autosomal gene for TXREB, and Northern blot hybridization with the 599-bp putative intron probe confirmed that the sequence is not part of the mature mRNA. Further analysis showed that the gene is expressed in a variety of human tissues and that the pseudogene is located between the genes for the proteins p55 and G6PD.
