THE DROSOPHILA-MELANOGASTER SIMILAR BHLH-PAS GENE ENCODES A PROTEIN RELATED TO HUMAN HYPOXIA-INDUCIBLE FACTOR 1-ALPHA AND DROSOPHILA SINGLE-MINDED

The Drosophila melanogaster (Dm) similar (sima) gene was isolated usin g a low-stringency hybridization screen employing a Dm single-minded g ene basic helix-loop-helix (bHLH) DNA probe. sima is a member of the b HLH-PAS gene family and the conceptual protein shares a number of stru ctural features, including a bHLH domain, PAS domain, and homopolymeri c amino acid stretches. Sima is most closely related to the human hypo xia-inducible factor 1 alpha bHLH-PAS protein. In situ hybridization e xperiments reveal that sima is transcribed in most or all cells throug hout embryogenesis. It has been cytologically mapped to position 99D o n the third chromosome, and is not closely linked to other known bHLH- PAS genes.