Alternative messenger RNA forms and open reading frames within an additional conserved region of the human PAX-2 gene.

PAX-2 is a member of a family of genes containing a highly conserved paired box domain. The paired box domain encodes a DNA binding motif, indicating that PAX proteins may function as transcriptional regulators, participating in a hierarchical network of gene regulation during embryogenesis. In this report, we provide evidence that there is an additional conserved region near the predicted COOH-terminus of PAX-2, PAX-5, and PAX-8. We also describe alternative splicing of a conserved 83-nucleotide segment in the 3' coding sequence of the PAX-2 gene. PAX-2 transcripts that contain the 83-nucleotide insertion encode a putative protein with an alternative COOH-terminus. The presence of an additional conserved region and alternative splicing within the predicted COOH-terminal region of several PAX genes has implications for the evolutionary origins and for the DNA binding site specificity of PAX-2, PAX-5, and PAX-8.