Structure and DNA-binding properties of Pax-QNR, a paired box- and homeobox-containing gene.

After differential screening of a complementary DNA library constructed from quail neuroretina cells (QNR) infected with the v-myc-containing avian retrovirus MC29, we have isolated a complementary DNA clone which identifies a mRNA essentially expressed in the neuronal layer of the retina. This complementary DNA encodes a protein containing paired box and homeobox domains. This gene, called Pax-QNR, is homologous to the murine Pax-6 and human AN genes, which are mutated in the autosomal dominant mutation small eye (Sey) of the mouse and aniridia in humans. Here, we report the genomic exon-intron organization, as well as the existence of alternative splicing events taking place at both the 5' end and the middle part of the gene. A Pax-QNR clone translated in reticulocyte lysate directed the synthesis of a 46 kilodalton protein able to bind specifically to the e5 sequence present upstream of the Drosophila even-skipped gene and target of the Drosophila paired protein. The Pax-QNR paired and homeobox domains individually expressed in bacteria are both able to recognize the e5 sequence.