Abstract
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.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Binding Sites
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Cell Membrane / metabolism
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Drosophila
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Drosophila Proteins*
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Eye Proteins / metabolism*
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Guanine Nucleotide Exchange Factors
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Insect Hormones / physiology
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Membrane Glycoproteins / metabolism*
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Membrane Proteins / chemistry
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Membrane Proteins / metabolism*
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Photoreceptor Cells, Invertebrate / cytology
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Photoreceptor Cells, Invertebrate / metabolism
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Proteins / metabolism*
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Receptor Protein-Tyrosine Kinases / metabolism*
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Signal Transduction
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Son of Sevenless Proteins
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ras Guanine Nucleotide Exchange Factors
Substances
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Drosophila Proteins
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Eye Proteins
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Guanine Nucleotide Exchange Factors
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Insect Hormones
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Membrane Glycoproteins
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Membrane Proteins
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Proteins
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Son of Sevenless Proteins
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drk protein, Drosophila
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ras Guanine Nucleotide Exchange Factors
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Receptor Protein-Tyrosine Kinases
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sev protein, Drosophila