title: Extracellular domain of the boss transmembrane ligand acts as an antagonist of the sev receptor.
abstract: The fate of the R7 photoreceptor cell in the Drosophila compound eye is established by a specific inductive interaction between the R8 photoreceptor neuron and the R7 precursor cell. This induction is mediated by two cell-surface proteins: the ligand, bride of sevenless (boss), and sevenless (sev), a tyrosine-kinase receptor. The structure of boss is unique for a ligand of a tyrosine-kinase receptor. It contains a large extracellular domain, seven transmembrane segments, and a carboxy-terminal cytoplasmic tail. Here we report that: (1) boss activates tyrosine phosphorylation of the sev receptor; (2) the seven transmembrane domain of boss is necessary for its function; and (3) a soluble form of boss acts as an antagonist of the sev receptor both in vivo and in vitro.
authors.affiliation: Howard Hughes Medical Institute, Department of Biological Chemistry, University of California, Los Angeles 90024.
authors.forename: A C
authors.initials: AC
authors.lastname: Hart
authors.forename: H
authors.initials: H
authors.lastname: Krämer
authors.forename: S L
authors.initials: SL
authors.lastname: Zipursky
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D001426:Bacterial Proteins; D002460:Cell Line; D004330:Drosophila / Q000235:genetics / Q000502:physiology*; D029721:Drosophila Proteins; D005136:Eye Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D015870:Gene Expression; D007700:Kinetics; D008024:Ligands; D008562:Membrane Glycoproteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D009474:Neurons / Q000502:physiology; D019000:Phosphotyrosine; D010786:Photoreceptor Cells / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D020794:Receptor Protein-Tyrosine Kinases; D011956:Receptors, Cell Surface / Q000235:genetics / Q000502:physiology*; D018000:Receptors, Peptide; D014162:Transfection; D014443:Tyrosine / Q000031:analogs & derivatives / Q000032:analysis
chemical_list: D000911:Antibodies, Monoclonal; D001426:Bacterial Proteins; D029721:Drosophila Proteins; D005136:Eye Proteins; D008024:Ligands; D008562:Membrane Glycoproteins; D011956:Receptors, Cell Surface; D018000:Receptors, Peptide; C072141:boss protein, Drosophila; D019000:Phosphotyrosine; D014443:Tyrosine; C079893:ypkA protein, Yersinia; D011505:Protein-Tyrosine Kinases; D020794:Receptor Protein-Tyrosine Kinases; C056737:sev protein, Drosophila; D017346:Protein Serine-Threonine Kinases