PMCCPMCCPMCC

Search tips
Search criteria 

Advanced

 
Logo of molcellbPermissionsJournals.ASM.orgJournalMCB ArticleJournal InfoAuthorsReviewers
 
Mol Cell Biol. 1996 September; 16(9): 4869–4878.
PMCID: PMC231489

The Ras GTPase-activating-protein-related human protein IQGAP2 harbors a potential actin binding domain and interacts with calmodulin and Rho family GTPases.

Abstract

We previously described IQGAP1 as a human protein related to a putative Ras GTPase-activating protein (RasGAP) from the fission yeast Schizosaccharomyces pombe. Here we report the identification of a liver-specific human protein that is 62% identical to IQGAP1. Like IQGAP1, the novel IQGAP2 protein harbors an N-terminal calponin homology motif which functions as an F-actin binding domain in members of the spectrin, filamin, and fimbrin families. Both IQGAPs also harbor several copies of a novel 50- to 55-amino-acid repeat, a single WW domain, and four IQ motifs and have 25% sequence identity with almost the entire S. pombe sar1 RasGAP homolog. As predicted by the presence of IQ motifs, IQGAP2 binds calmodulin. However, neither full-length nor truncated IQGAP2 stimulated the GTPase activity of Ras or its close relatives. Instead, IQGAP2 binds Cdc42 and Racl but not RhoA. This interaction involves the C-terminal half of IQGAP2 and appears to be independent of the nucleotide binding status of the GTPases. Although IQGAP2 shows no GAP activity towards Cdc42 and Rac1, the protein did inhibit both the intrinsic and RhoGAP-stimulated GTP hydrolysis rates of Cdc42 and Rac1, suggesting an alternative mechanism via which IQGAPs might modulate signaling by these GTPases. Since IQGAPs harbor a potential actin binding domain, they could play roles in the Cdc42 and Rac1 controlled generation of specific actin structures.

Full Text

The Full Text of this article is available as a PDF (1.0M).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.
  • Alexander KA, Wakim BT, Doyle GS, Walsh KA, Storm DR. Identification and characterization of the calmodulin-binding domain of neuromodulin, a neurospecific calmodulin-binding protein. J Biol Chem. 1988 Jun 5;263(16):7544–7549. [PubMed]
  • Altschul SF, Gish W, Miller W, Myers EW, Lipman DJ. Basic local alignment search tool. J Mol Biol. 1990 Oct 5;215(3):403–410. [PubMed]
  • André B, Springael JY. WWP, a new amino acid motif present in single or multiple copies in various proteins including dystrophin and the SH3-binding Yes-associated protein YAP65. Biochem Biophys Res Commun. 1994 Dec 15;205(2):1201–1205. [PubMed]
  • Ayme-Southgate A, Lasko P, French C, Pardue ML. Characterization of the gene for mp20: a Drosophila muscle protein that is not found in asynchronous oscillatory flight muscle. J Cell Biol. 1989 Feb;108(2):521–531. [PMC free article] [PubMed]
  • Barfod ET, Zheng Y, Kuang WJ, Hart MJ, Evans T, Cerione RA, Ashkenazi A. Cloning and expression of a human CDC42 GTPase-activating protein reveals a functional SH3-binding domain. J Biol Chem. 1993 Dec 15;268(35):26059–26062. [PubMed]
  • Boguski MS, McCormick F. Proteins regulating Ras and its relatives. Nature. 1993 Dec 16;366(6456):643–654. [PubMed]
  • Bollag G, McCormick F. Differential regulation of rasGAP and neurofibromatosis gene product activities. Nature. 1991 Jun 13;351(6327):576–579. [PubMed]
  • Bourne HR, Sanders DA, McCormick F. The GTPase superfamily: a conserved switch for diverse cell functions. Nature. 1990 Nov 8;348(6297):125–132. [PubMed]
  • Bourne HR, Sanders DA, McCormick F. The GTPase superfamily: conserved structure and molecular mechanism. Nature. 1991 Jan 10;349(6305):117–127. [PubMed]
  • Burgess WH, Jemiolo DK, Kretsinger RH. Interaction of calcium and calmodulin in the presence of sodium dodecyl sulfate. Biochim Biophys Acta. 1980 Jun 26;623(2):257–270. [PubMed]
  • Castresana J, Saraste M. Does Vav bind to F-actin through a CH domain? FEBS Lett. 1995 Oct 30;374(2):149–151. [PubMed]
  • Chan DC, Bedford MT, Leder P. Formin binding proteins bear WWP/WW domains that bind proline-rich peptides and functionally resemble SH3 domains. EMBO J. 1996 Mar 1;15(5):1045–1054. [PubMed]
  • Cheney RE, Mooseker MS. Unconventional myosins. Curr Opin Cell Biol. 1992 Feb;4(1):27–35. [PubMed]
  • Cheney RE, O'Shea MK, Heuser JE, Coelho MV, Wolenski JS, Espreafico EM, Forscher P, Larson RE, Mooseker MS. Brain myosin-V is a two-headed unconventional myosin with motor activity. Cell. 1993 Oct 8;75(1):13–23. [PubMed]
  • Devereux J, Haeberli P, Smithies O. A comprehensive set of sequence analysis programs for the VAX. Nucleic Acids Res. 1984 Jan 11;12(1 Pt 1):387–395. [PMC free article] [PubMed]
  • Eva A, Aaronson SA. Isolation of a new human oncogene from a diffuse B-cell lymphoma. Nature. 1985 Jul 18;316(6025):273–275. [PubMed]
  • Farnsworth CL, Freshney NW, Rosen LB, Ghosh A, Greenberg ME, Feig LA. Calcium activation of Ras mediated by neuronal exchange factor Ras-GRF. Nature. 1995 Aug 10;376(6540):524–527. [PubMed]
  • Feinberg AP, Vogelstein B. A technique for radiolabeling DNA restriction endonuclease fragments to high specific activity. Anal Biochem. 1983 Jul 1;132(1):6–13. [PubMed]
  • Foster R, Hu KQ, Lu Y, Nolan KM, Thissen J, Settleman J. Identification of a novel human Rho protein with unusual properties: GTPase deficiency and in vivo farnesylation. Mol Cell Biol. 1996 Jun;16(6):2689–2699. [PMC free article] [PubMed]
  • Fukui Y, Kozasa T, Kaziro Y, Takeda T, Yamamoto M. Role of a ras homolog in the life cycle of Schizosaccharomyces pombe. Cell. 1986 Jan 31;44(2):329–336. [PubMed]
  • Geissler EN, Liao M, Brook JD, Martin FH, Zsebo KM, Housman DE, Galli SJ. Stem cell factor (SCF), a novel hematopoietic growth factor and ligand for c-kit tyrosine kinase receptor, maps on human chromosome 12 between 12q14.3 and 12qter. Somat Cell Mol Genet. 1991 Mar;17(2):207–214. [PubMed]
  • Hall A, Self AJ. The effect of Mg2+ on the guanine nucleotide exchange rate of p21N-ras. J Biol Chem. 1986 Aug 25;261(24):10963–10965. [PubMed]
  • Hart MJ, Callow MG, Souza B, Polakis P. IQGAP1, a calmodulin-binding protein with a rasGAP-related domain, is a potential effector for cdc42Hs. EMBO J. 1996 Jun 17;15(12):2997–3005. [PubMed]
  • Imai Y, Miyake S, Hughes DA, Yamamoto M. Identification of a GTPase-activating protein homolog in Schizosaccharomyces pombe. Mol Cell Biol. 1991 Jun;11(6):3088–3094. [PMC free article] [PubMed]
  • Janknecht R, de Martynoff G, Lou J, Hipskind RA, Nordheim A, Stunnenberg HG. Rapid and efficient purification of native histidine-tagged protein expressed by recombinant vaccinia virus. Proc Natl Acad Sci U S A. 1991 Oct 15;88(20):8972–8976. [PubMed]
  • Katzav S, Cleveland JL, Heslop HE, Pulido D. Loss of the amino-terminal helix-loop-helix domain of the vav proto-oncogene activates its transforming potential. Mol Cell Biol. 1991 Apr;11(4):1912–1920. [PMC free article] [PubMed]
  • Lancaster CA, Taylor-Harris PM, Self AJ, Brill S, van Erp HE, Hall A. Characterization of rhoGAP. A GTPase-activating protein for rho-related small GTPases. J Biol Chem. 1994 Jan 14;269(2):1137–1142. [PubMed]
  • Lupas A, Van Dyke M, Stock J. Predicting coiled coils from protein sequences. Science. 1991 May 24;252(5009):1162–1164. [PubMed]
  • Manser E, Leung T, Salihuddin H, Tan L, Lim L. A non-receptor tyrosine kinase that inhibits the GTPase activity of p21cdc42. Nature. 1993 May 27;363(6427):364–367. [PubMed]
  • Manser E, Leung T, Salihuddin H, Zhao ZS, Lim L. A brain serine/threonine protein kinase activated by Cdc42 and Rac1. Nature. 1994 Jan 6;367(6458):40–46. [PubMed]
  • Marcus S, Polverino A, Chang E, Robbins D, Cobb MH, Wigler MH. Shk1, a homolog of the Saccharomyces cerevisiae Ste20 and mammalian p65PAK protein kinases, is a component of a Ras/Cdc42 signaling module in the fission yeast Schizosaccharomyces pombe. Proc Natl Acad Sci U S A. 1995 Jun 20;92(13):6180–6184. [PubMed]
  • Morgenstern JP, Land H. A series of mammalian expression vectors and characterisation of their expression of a reporter gene in stably and transiently transfected cells. Nucleic Acids Res. 1990 Feb 25;18(4):1068–1068. [PMC free article] [PubMed]
  • Nadin-Davis SA, Nasim A, Beach D. Involvement of ras in sexual differentiation but not in growth control in fission yeast. EMBO J. 1986 Nov;5(11):2963–2971. [PubMed]
  • Nakafuku M, Nagamine M, Ohtoshi A, Tanaka K, Toh-e A, Kaziro Y. Suppression of oncogenic Ras by mutant neurofibromatosis type 1 genes with single amino acid substitutions. Proc Natl Acad Sci U S A. 1993 Jul 15;90(14):6706–6710. [PubMed]
  • Nobes CD, Hall A. Rho, rac, and cdc42 GTPases regulate the assembly of multimolecular focal complexes associated with actin stress fibers, lamellipodia, and filopodia. Cell. 1995 Apr 7;81(1):53–62. [PubMed]
  • Pelletier J, Brook JD, Housman DE. Assignment of two of the translation initiation factor-4E (EIF4EL1 and EIF4EL2) genes to human chromosomes 4 and 20. Genomics. 1991 Aug;10(4):1079–1082. [PubMed]
  • Qiu RG, Chen J, Kirn D, McCormick F, Symons M. An essential role for Rac in Ras transformation. Nature. 1995 Mar 30;374(6521):457–459. [PubMed]
  • Ridley AJ, Hall A. The small GTP-binding protein rho regulates the assembly of focal adhesions and actin stress fibers in response to growth factors. Cell. 1992 Aug 7;70(3):389–399. [PubMed]
  • Ridley AJ, Paterson HF, Johnston CL, Diekmann D, Hall A. The small GTP-binding protein rac regulates growth factor-induced membrane ruffling. Cell. 1992 Aug 7;70(3):401–410. [PubMed]
  • Snijders AJ, Haase VH, Bernards A. Four tissue-specific mouse ltk mRNAs predict tyrosine kinases that differ upstream of their transmembrane segment. Oncogene. 1993 Jan;8(1):27–35. [PubMed]
  • Sudol M, Chen HI, Bougeret C, Einbond A, Bork P. Characterization of a novel protein-binding module--the WW domain. FEBS Lett. 1995 Aug 1;369(1):67–71. [PubMed]
  • Symons M, Derry JM, Karlak B, Jiang S, Lemahieu V, Mccormick F, Francke U, Abo A. Wiskott-Aldrich syndrome protein, a novel effector for the GTPase CDC42Hs, is implicated in actin polymerization. Cell. 1996 Mar 8;84(5):723–734. [PubMed]
  • Vogel US, Dixon RA, Schaber MD, Diehl RE, Marshall MS, Scolnick EM, Sigal IS, Gibbs JB. Cloning of bovine GAP and its interaction with oncogenic ras p21. Nature. 1988 Sep 1;335(6185):90–93. [PubMed]
  • Wang Y, Boguski M, Riggs M, Rodgers L, Wigler M. sar1, a gene from Schizosaccharomyces pombe encoding a protein that regulates ras1. Cell Regul. 1991 Jun;2(6):453–465. [PMC free article] [PubMed]
  • Weissbach L, Settleman J, Kalady MF, Snijders AJ, Murthy AE, Yan YX, Bernards A. Identification of a human rasGAP-related protein containing calmodulin-binding motifs. J Biol Chem. 1994 Aug 12;269(32):20517–20521. [PubMed]
  • Wilson R, Ainscough R, Anderson K, Baynes C, Berks M, Bonfield J, Burton J, Connell M, Copsey T, Cooper J, et al. 2.2 Mb of contiguous nucleotide sequence from chromosome III of C. elegans. Nature. 1994 Mar 3;368(6466):32–38. [PubMed]
  • Winder SJ, Walsh MP. Calponin: thin filament-linked regulation of smooth muscle contraction. Cell Signal. 1993 Nov;5(6):677–686. [PubMed]
  • Zhang K, DeClue JE, Vass WC, Papageorge AG, McCormick F, Lowy DR. Suppression of c-ras transformation by GTPase-activating protein. Nature. 1990 Aug 23;346(6286):754–756. [PubMed]
  • Zhang XF, Settleman J, Kyriakis JM, Takeuchi-Suzuki E, Elledge SJ, Marshall MS, Bruder JT, Rapp UR, Avruch J. Normal and oncogenic p21ras proteins bind to the amino-terminal regulatory domain of c-Raf-1. Nature. 1993 Jul 22;364(6435):308–313. [PubMed]

Articles from Molecular and Cellular Biology are provided here courtesy of American Society for Microbiology (ASM)