CLONING AND DEVELOPMENTAL EXPRESSION OF GRG, A MOUSE GENE-RELATED TO THE GROUCHO TRANSCRIPT OF THE DROSOPHILA-ENHANCER OF SPLIT COMPLEX

Genes of the Enhancer of split complex are involved in neural-epiderma l cell fate decisions during early embryogenesis in Drosophila. One of these genes, the product of the Enhancer of split m9/10 or groucho tr anscript, encodes a ubiquitous nuclear protein with homology at the ca rboxy-terminus to G-protein beta-subunits. Here we describe the clonin g and RNA expression analysis of a mouse gene, designated Grg, that is homologous to just the amino-terminal region of the groucho product. Grg encodes a 197 amino acid protein that shares 53% amino acid identi ty with the corresponding region of the product of the Drosophila grou cho gene. However, the mouse Grg protein does not contain the region h omologous to G-protein beta-subunits. An analysis by in situ hybridiza tion of the spatial and temporal localization of Grg RNA expression re vealed that, while the initial pattern of Grg expression was quite res tricted, by midgestation Grg RNA was ubiquitously expressed in the dev eloping embryo. Widespread Grg RNA expression was maintained in adult mice. The implications of these results for the existence of separable functional domains of the Drosophila groucho product, and possible ro les of the Grg gene during mouse development, are discussed.