ISOLATION AND CHARACTERIZATION OF MURINE HOMOLOGS OF THE DROSOPHILA 7INABSENTIA GENE (SINA)

The seven in absentia gene (sina) is required for formation of the R7 photoreceptor cell in the developing eye of Drosophila melanogaster. T he sina protein contains a putative zinc finger domain and localises t o the cell nucleus in Drosophila. We report here the identification of a family of genes in the mouse (designated Siah) with extensive seque nce homology to Drosophila sina. The Siah genes fall into two main gro ups: Siah-1, which consists of four closely related members, two of wh ich appear to be functional, and Siah-2, which contains a single funct ional member. The predicted Siah proteins show an unusually high degre e of conservation with sina over the majority of their lengths, diverg ing significantly only at their amino terminal ends. The Siah-1 and Si ah-2 genes are widely expressed at a low level in the embryo and adult . Analysis of Siah-2 by hybridisation histochemistry shows that it is expressed at a higher level in a restricted number of sites during dev elopment, including the olfactory epithelium, retina, forebrain and pr oliferating cartilage of developing bone. The striking degree of seque nce homology observed between the Drosophila and murine genes implies strong conservation pressure on the Siah genes and suggests that they play a significant role in vertebrate development.