CHARACTERIZATION AND RELATIONSHIP OF DPP RECEPTORS ENCODED BY THE SAXOPHONE AND THICK VEINS GENES IN DROSOPHILA

The dpp/BMP family of TGF beta-related factors controls numerous event s in pattern formation and morphogenesis. How these polypeptide signal s are received and transduced by target cells is largely unknown. We c ombine molecular and genetic approaches to establish that the Drosophi la saxophone (sax) gene encodes a dpp receptor. We compare the structu ral properties and expression patterns of sax with a second dpp recept or encoded by the thick veins (tkv) gene. While the sax gene is expres sed ubiquitously, tkv is expressed in a highly localized and dynamic p attern during development. Some, but not all, of the tkv expression pa ttern parallels that of dpp. Ubiquitous expression of a tkv transgene rescues both tkv and sax loss-of function mutations. Thus, there is at least partial functional overlap of the sax and tkv receptors in vivo . We consider these observations in terms of possible ligand-receptor interactions during Drosophila development.