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. 1996 Sep;16(9):4869–4878. doi: 10.1128/mcb.16.9.4869

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

S Brill 1, S Li 1, C W Lyman 1, D M Church 1, J J Wasmuth 1, L Weissbach 1, A Bernards 1, A J Snijders 1
PMCID: PMC231489  PMID: 8756646

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.

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Selected References

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  1. Alexander K. A., Wakim B. T., Doyle G. S., Walsh K. A., Storm D. R. 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] [Google Scholar]
  2. Altschul S. F., Gish W., Miller W., Myers E. W., Lipman D. J. Basic local alignment search tool. J Mol Biol. 1990 Oct 5;215(3):403–410. doi: 10.1016/S0022-2836(05)80360-2. [DOI] [PubMed] [Google Scholar]
  3. André B., Springael J. Y. 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. doi: 10.1006/bbrc.1994.2793. [DOI] [PubMed] [Google Scholar]
  4. Ayme-Southgate A., Lasko P., French C., Pardue M. L. 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. doi: 10.1083/jcb.108.2.521. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Barfod E. T., Zheng Y., Kuang W. J., Hart M. J., Evans T., Cerione R. A., 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] [Google Scholar]
  6. Boguski M. S., McCormick F. Proteins regulating Ras and its relatives. Nature. 1993 Dec 16;366(6456):643–654. doi: 10.1038/366643a0. [DOI] [PubMed] [Google Scholar]
  7. Bollag G., McCormick F. Differential regulation of rasGAP and neurofibromatosis gene product activities. Nature. 1991 Jun 13;351(6327):576–579. doi: 10.1038/351576a0. [DOI] [PubMed] [Google Scholar]
  8. Bourne H. R., Sanders D. A., McCormick F. The GTPase superfamily: a conserved switch for diverse cell functions. Nature. 1990 Nov 8;348(6297):125–132. doi: 10.1038/348125a0. [DOI] [PubMed] [Google Scholar]
  9. Bourne H. R., Sanders D. A., McCormick F. The GTPase superfamily: conserved structure and molecular mechanism. Nature. 1991 Jan 10;349(6305):117–127. doi: 10.1038/349117a0. [DOI] [PubMed] [Google Scholar]
  10. Burgess W. H., Jemiolo D. K., Kretsinger R. H. Interaction of calcium and calmodulin in the presence of sodium dodecyl sulfate. Biochim Biophys Acta. 1980 Jun 26;623(2):257–270. doi: 10.1016/0005-2795(80)90254-8. [DOI] [PubMed] [Google Scholar]
  11. Castresana J., Saraste M. Does Vav bind to F-actin through a CH domain? FEBS Lett. 1995 Oct 30;374(2):149–151. doi: 10.1016/0014-5793(95)01098-y. [DOI] [PubMed] [Google Scholar]
  12. Chan D. C., Bedford M. T., 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. [PMC free article] [PubMed] [Google Scholar]
  13. Cheney R. E., Mooseker M. S. Unconventional myosins. Curr Opin Cell Biol. 1992 Feb;4(1):27–35. doi: 10.1016/0955-0674(92)90055-h. [DOI] [PubMed] [Google Scholar]
  14. Cheney R. E., O'Shea M. K., Heuser J. E., Coelho M. V., Wolenski J. S., Espreafico E. M., Forscher P., Larson R. E., Mooseker M. S. Brain myosin-V is a two-headed unconventional myosin with motor activity. Cell. 1993 Oct 8;75(1):13–23. doi: 10.1016/S0092-8674(05)80080-7. [DOI] [PubMed] [Google Scholar]
  15. 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. doi: 10.1093/nar/12.1part1.387. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Eva A., Aaronson S. A. Isolation of a new human oncogene from a diffuse B-cell lymphoma. Nature. 1985 Jul 18;316(6025):273–275. doi: 10.1038/316273a0. [DOI] [PubMed] [Google Scholar]
  17. Farnsworth C. L., Freshney N. W., Rosen L. B., Ghosh A., Greenberg M. E., Feig L. A. Calcium activation of Ras mediated by neuronal exchange factor Ras-GRF. Nature. 1995 Aug 10;376(6540):524–527. doi: 10.1038/376524a0. [DOI] [PubMed] [Google Scholar]
  18. Feinberg A. P., Vogelstein B. A technique for radiolabeling DNA restriction endonuclease fragments to high specific activity. Anal Biochem. 1983 Jul 1;132(1):6–13. doi: 10.1016/0003-2697(83)90418-9. [DOI] [PubMed] [Google Scholar]
  19. Foster R., Hu K. Q., Lu Y., Nolan K. M., 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. doi: 10.1128/mcb.16.6.2689. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. 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. doi: 10.1016/0092-8674(86)90767-1. [DOI] [PubMed] [Google Scholar]
  21. Geissler E. N., Liao M., Brook J. D., Martin F. H., Zsebo K. M., Housman D. E., Galli S. J. 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. doi: 10.1007/BF01232978. [DOI] [PubMed] [Google Scholar]
  22. Hall A., Self A. J. The effect of Mg2+ on the guanine nucleotide exchange rate of p21N-ras. J Biol Chem. 1986 Aug 25;261(24):10963–10965. [PubMed] [Google Scholar]
  23. Hart M. J., Callow M. G., 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. [PMC free article] [PubMed] [Google Scholar]
  24. Imai Y., Miyake S., Hughes D. A., Yamamoto M. Identification of a GTPase-activating protein homolog in Schizosaccharomyces pombe. Mol Cell Biol. 1991 Jun;11(6):3088–3094. doi: 10.1128/mcb.11.6.3088. [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. Janknecht R., de Martynoff G., Lou J., Hipskind R. A., Nordheim A., Stunnenberg H. G. 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. doi: 10.1073/pnas.88.20.8972. [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. Katzav S., Cleveland J. L., Heslop H. E., 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. doi: 10.1128/mcb.11.4.1912. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. Lancaster C. A., Taylor-Harris P. M., Self A. J., Brill S., van Erp H. E., 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] [Google Scholar]
  28. Lupas A., Van Dyke M., Stock J. Predicting coiled coils from protein sequences. Science. 1991 May 24;252(5009):1162–1164. doi: 10.1126/science.252.5009.1162. [DOI] [PubMed] [Google Scholar]
  29. 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. doi: 10.1038/363364a0. [DOI] [PubMed] [Google Scholar]
  30. Manser E., Leung T., Salihuddin H., Zhao Z. S., Lim L. A brain serine/threonine protein kinase activated by Cdc42 and Rac1. Nature. 1994 Jan 6;367(6458):40–46. doi: 10.1038/367040a0. [DOI] [PubMed] [Google Scholar]
  31. Marcus S., Polverino A., Chang E., Robbins D., Cobb M. H., Wigler M. H. 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. doi: 10.1073/pnas.92.13.6180. [DOI] [PMC free article] [PubMed] [Google Scholar]
  32. Morgenstern J. P., 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. doi: 10.1093/nar/18.4.1068. [DOI] [PMC free article] [PubMed] [Google Scholar]
  33. Nadin-Davis S. A., 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. doi: 10.1002/j.1460-2075.1986.tb04593.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  34. 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. doi: 10.1073/pnas.90.14.6706. [DOI] [PMC free article] [PubMed] [Google Scholar]
  35. Nobes C. D., 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. doi: 10.1016/0092-8674(95)90370-4. [DOI] [PubMed] [Google Scholar]
  36. Pelletier J., Brook J. D., Housman D. E. 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. doi: 10.1016/0888-7543(91)90203-q. [DOI] [PubMed] [Google Scholar]
  37. Qiu R. G., Chen J., Kirn D., McCormick F., Symons M. An essential role for Rac in Ras transformation. Nature. 1995 Mar 30;374(6521):457–459. doi: 10.1038/374457a0. [DOI] [PubMed] [Google Scholar]
  38. Ridley A. J., 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. doi: 10.1016/0092-8674(92)90163-7. [DOI] [PubMed] [Google Scholar]
  39. Ridley A. J., Paterson H. F., Johnston C. L., Diekmann D., Hall A. The small GTP-binding protein rac regulates growth factor-induced membrane ruffling. Cell. 1992 Aug 7;70(3):401–410. doi: 10.1016/0092-8674(92)90164-8. [DOI] [PubMed] [Google Scholar]
  40. Snijders A. J., Haase V. H., 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] [Google Scholar]
  41. Sudol M., Chen H. I., 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. doi: 10.1016/0014-5793(95)00550-s. [DOI] [PubMed] [Google Scholar]
  42. Symons M., Derry J. M., 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. doi: 10.1016/s0092-8674(00)81050-8. [DOI] [PubMed] [Google Scholar]
  43. Vogel U. S., Dixon R. A., Schaber M. D., Diehl R. E., Marshall M. S., Scolnick E. M., Sigal I. S., Gibbs J. B. Cloning of bovine GAP and its interaction with oncogenic ras p21. Nature. 1988 Sep 1;335(6185):90–93. doi: 10.1038/335090a0. [DOI] [PubMed] [Google Scholar]
  44. 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. doi: 10.1091/mbc.2.6.453. [DOI] [PMC free article] [PubMed] [Google Scholar]
  45. Weissbach L., Settleman J., Kalady M. F., Snijders A. J., Murthy A. E., Yan Y. X., Bernards A. Identification of a human rasGAP-related protein containing calmodulin-binding motifs. J Biol Chem. 1994 Aug 12;269(32):20517–20521. [PubMed] [Google Scholar]
  46. Wilson R., Ainscough R., Anderson K., Baynes C., Berks M., Bonfield J., Burton J., Connell M., Copsey T., Cooper J. 2.2 Mb of contiguous nucleotide sequence from chromosome III of C. elegans. Nature. 1994 Mar 3;368(6466):32–38. doi: 10.1038/368032a0. [DOI] [PubMed] [Google Scholar]
  47. Winder S. J., Walsh M. P. Calponin: thin filament-linked regulation of smooth muscle contraction. Cell Signal. 1993 Nov;5(6):677–686. doi: 10.1016/0898-6568(93)90029-l. [DOI] [PubMed] [Google Scholar]
  48. Zhang K., DeClue J. E., Vass W. C., Papageorge A. G., McCormick F., Lowy D. R. Suppression of c-ras transformation by GTPase-activating protein. Nature. 1990 Aug 23;346(6286):754–756. doi: 10.1038/346754a0. [DOI] [PubMed] [Google Scholar]
  49. Zhang X. F., Settleman J., Kyriakis J. M., Takeuchi-Suzuki E., Elledge S. J., Marshall M. S., Bruder J. T., Rapp U. R., 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. doi: 10.1038/364308a0. [DOI] [PubMed] [Google Scholar]

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