Identification of a gene within the tandem array of red and green color pigment genes.

The tandem array of color pigment genes on chromosome Xq28 contains nested exons of a distinct gene. This gene (termed TEX28) is composed of five exons that span almost the entire distance between the protein-coding regions of the color pigment genes and a transketolase-related gene. Although most of the TEX28 gene is repeated within the color pigment gene array, the exclusion of exon 1 from the array is predicted to restrict transcription to a single copy of the gene. The TEX28 gene encodes a polypeptide of 410 amino acid residues. This polypeptide does not display significant homology with any known proteins in public databases. Transcripts of the gene (1.8 kb) were detected in testes, but not in any other tissue examined. Color vision disorders that result from the deletion of color pigment genes should be reappraised for associated phenotypes that may derive from disruption of the TEX28 gene.