title: Isolated Sos1 PH domain exhibits germinal vesicle breakdown-inducing activity in Xenopus oocytes.
abstract: Purified, bacterially expressed PH domains of Sos1, IRS-1, betaARK, and PLCdelta1 were analyzed functionally by means of microinjection into full grown, stage VI Xenopus laevis oocytes. Whereas the PH domains from IRS-1, betaARK, or PLCdelta1 did not show any effect in the oocytes, injection of the purified Sos1 PH domain resulted in induction of significant rates of germinal vesicle breakdown and meiotic maturation. Furthermore, the Sos1 PH domain exhibited also significant synergy with insulin or coinjected normal Ras protein in induction of germinal vesicle breakdown, although it did not affect the rate of progesterone-induced maturation. These results suggest that purified, isolated PH domains retain, at least in part, their functional specificity and that Xenopus oocytes may constitute a useful biological system to analyze the functional role of the Sos1 PH domain in Ras signaling pathways.
authors.affiliation: Laboratory of Cellular and Molecular Biology, NCI, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: J
authors.initials: J
authors.lastname: Font de Mora
authors.forename: C
authors.initials: C
authors.lastname: Guerrero
authors.forename: D
authors.initials: D
authors.lastname: Mahadevan
authors.forename: J J
authors.initials: JJ
authors.lastname: Coque
authors.forename: J M
authors.initials: JM
authors.lastname: Rojas
authors.forename: L M
authors.initials: LM
authors.lastname: Esteban
authors.forename: M
authors.initials: M
authors.lastname: Rebecchi
authors.forename: E
authors.initials: E
authors.lastname: Santos
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001798:Blood Proteins / Q000235:genetics*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007328:Insulin / Q000494:pharmacology; D055504:Insulin Receptor Substrate Proteins; D007527:Isoenzymes / Q000378:metabolism; D008540:Meiosis; D008969:Molecular Sequence Data; D015513:Oncogene Proteins; D009865:Oocytes / Q000502:physiology*; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism*; D051966:Phospholipase C gamma; D010750:Phosphoproteins / Q000378:metabolism; D011374:Progesterone / Q000494:pharmacology; D011518:Proto-Oncogene Proteins; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D020837:SOS1 Protein; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D010738:Type C Phospholipases / Q000378:metabolism; D014981:Xenopus; D029867:Xenopus Proteins; D018631:ras Proteins / Q000378:metabolism; D000094963:Axl Receptor Tyrosine Kinase
chemical_list: D001798:Blood Proteins; D005656:Fungal Proteins; C526292:IRS1 protein, human; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; D007527:Isoenzymes; D015513:Oncogene Proteins; D010446:Peptide Fragments; D010750:Phosphoproteins; D011518:Proto-Oncogene Proteins; D012097:Repressor Proteins; D020837:SOS1 Protein; D029867:Xenopus Proteins; C526294:irs1 protein, Xenopus; C039077:platelet protein P47; D011374:Progesterone; D020794:Receptor Protein-Tyrosine Kinases; D010738:Type C Phospholipases; D051966:Phospholipase C gamma; D018631:ras Proteins; D000094963:Axl Receptor Tyrosine Kinase