RELATIONSHIP BETWEEN THE PRODUCT OF THE DROSOPHILA-ULTRASPIRACLE LOCUS AND THE VERTEBRATE RETINOID X-RECEPTOR

THE vitamin A derivative, retinoic acid, can regulate morpho-genesis and differentiation in vertebrates1,2. Two different sub-families of the steroid receptor superfamily of transcription factors, the retinoic acid receptors and the retinoid X receptor, mediate the effects of retinoic acid3-6. As part of an analysis of the hormonal control of development, we have examined the Drosophila genome for retinoic acid receptor homologues7. Here we describe one such gene, XR2C, which encodes a product with structural similarity to the human retinoic acid-responsive tran-scription factor, retinoid X receptor. This receptor-like protein is encoded by ultraspiracle (usp), a locus required both maternally and zygotically for pattern formation. The discovery that the usp product is a retinoid X receptor homologue suggests that similar chemical cues underlie morphogenic signalling in vertebrate and invertebrate systems. © 1990 Nature Publishing Group.