Analysis of transcription of the murine homeobox gene Hox 1.3

Development in Drosophila is critically dependent on the expression of classes of regulatory genes which establish the polarity of the organism (rev. Niisslein-Volhard et al.), define the segmentation (rev. Scott and Carroll), determine individual segmental characteristics (rev. Gehring), and establish neuronal identities (Doe et al.). These genes were discovered by the effects of mutations which disturbed embryogenesis. Many of the genes which take part in these processes in Drosophila have been characterized at the molecular level and, surprisingly, were found to share a 180 base pair region which is called the homeobox (Gehring). The homeobox encodes a sequence specific DNA binding region, the homeodomain, of these regulatory proteins which presumably modulate the expression of other genes in a coordinated fashion (Gehring; Scott and Carroll). Tremendous excitement was generated by the discovery that the homeobox is highly conserved not only between many developmentally important Drosophila genes, but also among many other organisms including sea urchins (Dolecki et al.), fish (Eiken et al.), frogs (Muller et al.), mice (McGinnis et al., Colberg-Poley et at. 1985a) and humans (Acampora et al.).