GSBS Student Publications


In vivo functional analysis of the Ras exchange factor son of sevenless

GSBS Program

Biochemistry & Molecular Pharmacology

UMMS Affiliation

Graduate School of Biomedical Sciences; Department of Biology and Molecular Biology; Program in Molecular Medicine



Document Type


Medical Subject Headings

Animals; Binding Sites; Cell Membrane; Drosophila; *Drosophila Proteins; Eye Proteins; Guanine Nucleotide Exchange Factors; Insect Hormones; Membrane Glycoproteins; Membrane Proteins; Photoreceptors, Invertebrate; Proteins; Receptor Protein-Tyrosine Kinases; Signal Transduction; Son of Sevenless Proteins; ras Guanine Nucleotide Exchange Factors


Life Sciences | Medicine and Health Sciences


The Son of sevenless (Sos) protein functions as a guanine nucleotide transfer factor for Ras and interacts with the receptor tyrosine kinase Sevenless through the protein Drk, a homolog of mammalian Grb2. In vivo structure-function analysis revealed that the amino terminus of Sos was essential for its function in flies. A molecule lacking the amino terminus was a potent dominant negative. In contrast, a Sos fragment lacking the Drk binding sites was functional and its activity was dependent on the presence of the Sevenless receptor. Furthermore, membrane localization of Sos was independent of Drk. A possible role for Drk as an activator of Sos is discussed and a Drk-independent interaction between Sos and Sevenless is proposed that is likely mediated by the pleckstrin homology domain within the amino terminus.

Rights and Permissions

Citation: Science. 1995 Apr 28;268(5210):576-9.

Related Resources

Link to article in PubMed

Journal Title

Science (New York, N.Y.)

PubMed ID