CLONING OF A DROSOPHILA-MELANOGASTER HOMOLOG OF THE MOUSE TYPE-I BONEMORPHOGENETIC PROTEINS-2 -4 RECEPTOR - A POTENTIAL DECAPENTAPLEGIC RECEPTOR/

The Drosophila melanogaster (Dot) decapentaplegic (dpp) gene product p lays an essential role during several stages of Dm development. The DP P protein is a member of the transforming growth factor-beta (TGF-beta ) superfamily and an orthologue of mammalian bone morphogenetic protei ns (BMP-2 and -4). Recently, a cDNA clone encoding the mouse Ser/Thr k inase receptor specific for BMP-2/-4 (mTFR11) was isolated. Here, we d escribe the deduced primary structure, the cytogenetic position and ex pression pattern of the Dm homologue of mTFR11 (DTFR), a putative DPP receptor. The cytogenetic position of the Dm dtfr gene was mapped to 2 5D. DTFR has striking homology to mTFR11, especially in the cytoplasmi c domain (approx. 63%), including a Ser + Gly-rich box that is charact eristic of type-I receptors for the TGF-P superfamily. Although the am ino acid (aa) sequence of the extracellular domain is less conserved t han that of the cytoplasmic domain, the extracellular domains of these two molecules were more homologous (approx. 27%) to each other than a ny other receptors for the TGF-beta superfamily. The spacing of Cys re sidues in the extracellular domain, which is considered crucial to lig and specificity, is highly conserved in these two receptors. During Dm embryonic development, its expression pattern changes in a dynamic fa shion with high levels of expression in mesoderm and midgut, with some relation to dpp mutant phenotypes.