Structure of a c-Kit Product Complex Reveals the Basis for Kinase Transactivation

The c-Kit proto-oncogene is a receptor protein-tyrosine kinase associated with several highly malignant human cancers. Upon binding its ligand, stem cell factor (SCF), c-Kit forms an active dimer that autophosphorylates itself and activates a signaling cascade that induces cell growth. Disease-causing human mutations that activate SCF-independent constitutive expression of c-Kit are found in acute myelogenous leukemia, human mast cell disease, and gastrointestinal stromal tumors. We report on the phosphorylation state and crystal structure of a c-Kit product complex. The c-Kit structure is in a fully active form, with ordered kinase activation and phosphate-binding loops. These results provide key insights into the molecular basis for c-Kit kinase transactivation to assist in the design of new competitive inhibitors targeting activated mutant forms of c-Kit that are resistant to current chemotherapy regimes. The c-Kit proto-oncogene is a receptor protein-tyrosine kinase associated with several highly malignant human cancers. Upon binding its ligand, stem cell factor (SCF), c-Kit forms an active dimer that autophosphorylates itself and activates a signaling cascade that induces cell growth. Disease-causing human mutations that activate SCF-independent constitutive expression of c-Kit are found in acute myelogenous leukemia, human mast cell disease, and gastrointestinal stromal tumors. We report on the phosphorylation state and crystal structure of a c-Kit product complex. The c-Kit structure is in a fully active form, with ordered kinase activation and phosphate-binding loops. These results provide key insights into the molecular basis for c-Kit kinase transactivation to assist in the design of new competitive inhibitors targeting activated mutant forms of c-Kit that are resistant to current chemotherapy regimes. Receptor protein-tyrosine kinases (RPTKs) 1The abbreviations used are: RPTK, receptor protein-tyrosine kinase; SCF, stem cell factor; LC, liquid chromatography; MS, mass spectrometry; MES, 2[N-morpholinoethanesulfonic acid; PTR, phosphotyrosine.1The abbreviations used are: RPTK, receptor protein-tyrosine kinase; SCF, stem cell factor; LC, liquid chromatography; MS, mass spectrometry; MES, 2[N-morpholinoethanesulfonic acid; PTR, phosphotyrosine. regulate key signal transduction cascades that control cellular growth and proliferation. The stem cell factor (SCF) receptor c-Kit is a type III transmembrane RPTK comprised of five extracellular immunoglobulin domains, a single transmembrane region, an inhibitory cytoplasmic juxtamembrane domain, and a split cytoplasmic kinase domain separated by a kinase insert segment (1Yarden Y. Escobedo J.A. Kuang W.-J. Yang-Feng T.L. Daniel T.O. Tremble P.M. Chen E.Y. Ando M.E. Harkins R.N. Francke U. Fried V.A. Ullrich A. Williams L.T. Nature. 1986; 323: 226-232Crossref PubMed Scopus (764) Google Scholar, 2Ullrich A. Schlessinger J. Cell. 1990; 61: 203-212Abstract Full Text PDF PubMed Scopus (4583) Google Scholar). The type III RPTK family includes c-Kit (3Yarden Y. Kuang W.-J. Yang-Feng T. Coussens L. Munemitsu S. Dull T.J. Chen E. Schlessinger J. Francke U. Ullrich A. EMBO J. 1987; 6: 3341-3351Crossref PubMed Scopus (1317) Google Scholar), the colonystimulating factor-1 (formerly FMS) (4Coussens L. Van Beveren C. Smith D. Chen E. Mitchell R.L. Isacke C.M. Verma I.M. Ullrich A. Nature. 1986; 320: 277-280Crossref PubMed Scopus (289) Google Scholar), the platelet-derived growth factor α and β receptors (1Yarden Y. Escobedo J.A. Kuang W.-J. Yang-Feng T.L. Daniel T.O. Tremble P.M. Chen E.Y. Ando M.E. Harkins R.N. Francke U. Fried V.A. Ullrich A. Williams L.T. Nature. 1986; 323: 226-232Crossref PubMed Scopus (764) Google Scholar, 5Claesson-Welsh L. Eriksson A. Westermark B. Heldin C.-H. Proc. Natl. Acad. Sci. U. S. A. 1989; 86: 4917-4921Crossref PubMed Scopus (307) Google Scholar), and the FMS-related receptor FLT-3 (6Rosnet O. Schiff C. Pebusque M.-J. Marchetto S. Tonnelle C. Toiron Y. Birg F. Birnbaum D. Blood. 1993; 82: 1110-1119Crossref PubMed Google Scholar). Signaling by RPTKs occurs via ligand binding to the extracellular IG domains, inducing the receptors to form dimers, and thereby activating intrinsic tyrosine kinase activity through the transphosphorylation of specific tyrosine residues in the juxtamembrane and kinase domains (7Heldin C.-H. Cell. 1995; 80: 213-223Abstract Full Text PDF PubMed Scopus (1427) Google Scholar, 8Weiss A. Schlessinger J. Cell. 1998; 94: 277-280Abstract Full Text Full Text PDF PubMed Scopus (338) Google Scholar). Ligand binding both activates kinase activity and creates tyrosine-phosphorylated receptors that mediate the specific binding of intracellular signaling proteins. Src homology 2 and protein tyrosine binding domains (9Blume-Jensen P. Hunter T. Nature. 2001; 411: 355-365Crossref PubMed Scopus (3099) Google Scholar), including the protein-tyrosine phosphatase SHP-1, act as negative regulators of c-Kit activity (10Kozlowski M. Larose L. Lee F. Le D.M. Rottapel R. Siminovitch K.A. Mol. Cell. Biol. 1998; 18: 2089-2099Crossref PubMed Scopus (176) Google Scholar). These cytoplasmic signaling proteins initiate serine/threonine phosphorylation cascades that activate transcription factors to determine specific cellular responses (Fig. 1).The human c-Kit gene is the cellular homologue of the v-kit oncogene found in the transforming Hardy-Zuckerman 4 feline sarcoma virus (11Snyder Jr., H.W. Broudeur D. Zuckerman E.E. Hardy W.D. Nature. 1986; 320: 415-421Crossref PubMed Scopus (450) Google Scholar) and encodes a 976-amino acid residue RPTK. Loss-of-function c-Kit mutations establish its importance for the normal growth of hematopoietic progenitor cells, mast cells, melanocytes, primordial germ cells, and the interstitial cells of Cajal (12Besmer P. Curr. Opin. Cell Biol. 1991; 3: 939-946Crossref PubMed Scopus (152) Google Scholar, 13Lyman S.D. Jacobsen S.E.W. Blood. 1998; 91: 1101-1134Crossref PubMed Google Scholar, 14Ashman L.K. Int. J. Biochem. Cell Biol. 1999; 31: 1037-1051Crossref PubMed Scopus (475) Google Scholar, 15Kitamura Y. Hirota S. Nishida T. Mutat. Res. 2001; 477: 165-171Crossref PubMed Scopus (60) Google Scholar). Gain-of-function mutations, resulting in SCF-independent, constitutive activation of c-Kit, are found in several highly malignant cancers. Mutations in the c-Kit juxtamembrane region cluster around the two main autophosphorylation sites that mediate protein tyrosine binding, Tyr-568 and Tyr-570, and are associated with human gastrointestinal stromal tumors (16Hirota S. Isozaki K. Moriyama Y. Hashimoto K. Nishida T. Ishiguro S. Kawano K. Hanada M. Kurata A. Takeda M. Tunio G.M. Matsuzawa Y. Kanakura Y. Sinomura Y. Kitamura Y. Science. 1998; 279: 577-580Crossref PubMed Scopus (3789) Google Scholar, 17Hirota S. M. Hashimoto K. Isozaki K. Kanakura Y. T. A. Kitamura Y. Nishida T. 1998; PubMed Scopus Google Scholar). Mutations in the kinase domain are found in mast cell and Y. Hirota S. Nishida T. Mutat. Res. 2001; 477: 165-171Crossref PubMed Scopus (60) Google Scholar) and in human germ cell tumors Jr., J. 1999; Full Text Full Text PDF PubMed Scopus Google mutations cells through c-Kit dimer two c-Kit kinases into to to act as and for (9Blume-Jensen P. Hunter T. Nature. 2001; 411: 355-365Crossref PubMed Scopus (3099) Google Scholar, M. Schlessinger J. J. Biol. 1998; Full Text Full Text PDF PubMed Scopus Google Scholar). The juxtamembrane domain c-Kit the binding of resulting in autophosphorylation and kinase The transforming kinase domain the active of the c-Kit activation mutations in residues in the and growth factor receptors are highly in ligand J. D.M. PubMed Scopus Google Scholar, Mol. Cell. Biol. PubMed Scopus Google Scholar) and are in and M. L. T. B. Proc. Natl. Acad. Sci. U. S. A. 94: PubMed Scopus Google Scholar, R. 1995; PubMed Scopus Google of mutant c-Kit RPTKs in human the targeting of the c-Kit kinase domain for The of by the and in the of myelogenous is on the of the is in normal the kinase structure with the kinase the binding sites for T. P. B. J. Science. PubMed Scopus Google Scholar). an for human including gastrointestinal stromal tumors and of c-Kit with activating mutations in the juxtamembrane is in with activating mutations in the c-Kit kinase domain Y. P. F. S. J. M. A. K. C. Y. M. O. M. O. P. PubMed Scopus Google Scholar). We report on the and the crystal structure of a c-Kit complex. These results provide the molecular basis for the of c-Kit kinase transactivation and is an for the design of specific c-Kit kinase and domain of the human gene (4Coussens L. Van Beveren C. Smith D. Chen E. Mitchell R.L. Isacke C.M. Verma I.M. Ullrich A. Nature. 1986; 320: 277-280Crossref PubMed Scopus (289) Google by a and into the and sites of to a the and The kinase domain residues and with c-Kit protein with a by an in of cells and c-Kit protein a of of cell and by binding to and with to and c-Kit protein with The with and by a The c-Kit protein as by mass and to in in liquid and by autophosphorylation by of and and with and the a in for a used to and the a and split to with the and on a protein used to the phosphorylation sites on the and of c-Kit kinase by active with and and by of protein and of MES, in with and by in liquid the and and Scopus Google Scholar). The to the a and and two in the and structure are in The structure by molecular J. A. Scopus Google Scholar) with the receptor kinase used as a The the in the and The in Biol. PubMed Scopus Google Scholar) and and J. Biol. 1999; PubMed Scopus Google Scholar). The with the and is the of for of in are for the is the of for of in are for the in a new the phosphorylation with the the the mass to to the of the The for the the of a of and to the (Fig. The and the phosphorylation sites to Tyr-568 and of the on the basis of a mass of of the and for the two residues Tyr-568 and on the mass the and for Tyr-568 and and for The the of the and structure of active c-Kit kinase is of and of the of an active kinase (Fig. The is and for the active and for of the structure and loops. of the residues in both in the are the of the of main and a of both is The acid residues of both are as are the residues the kinase The of both the and forms a key of the active are with an active kinase structure (Fig. of active c-Kit The the kinase and key including the phosphate-binding and kinase activation The of the and are of c-Kit kinase the protein serine/threonine kinase with a comprised of and a (Fig. The a single the control the and binding and kinase activity in The c-Kit is in a with The forms a with the of and the to the and of the The is in an active state with binding a that the and and the of an (Fig. c-Kit active the c-Kit active with and are and c-Kit active around the and in the the and the into a with the and to the and of the region residues and (Fig. The and the forms a with the The of the with the residue of the c-Kit The residues the with the active to the transphosphorylation (Fig. c-Kit kinase active is fully for autophosphorylation as by the of both residues the and in the These in the in by the of the and of the and with the of the III RPTK the tyrosine residues are to the kinase domain and the of the is for the to the autophosphorylation in of the is by a and and by and with residues the of the binding the active of the kinase the that the is of the that the c-Kit is in a active is of the of the residue with the of in the The of the on residues the negative of a and the in an active in c-Kit the of its constitutive activation in the normal state c-Kit receptor as a in the cell of induces the c-Kit receptor to as both and for c-Kit autophosphorylates specific tyrosine residues in protein kinases are and cellular residues are the signal that activates intracellular serine/threonine protein kinase signaling cascades to determine specific cellular responses in normal cellular growth and (Fig. We and the crystal structure of active c-Kit kinase to an of the molecular basis by activating c-Kit We autophosphorylation with a c-Kit that the tyrosine c-Kit to the Tyr-568 and are and two residues are the to are of and that the residue is the tyrosine residue to by the crystal structure of the active c-Kit in the is ordered and in an active phosphorylation of is to activate the These results are in with for kinases in phosphorylation of residues is to the kinase in an active state in M. J. Cell. Full Text Full Text PDF PubMed Scopus Google Scholar). in normal c-Kit receptor protein-tyrosine the kinase domain its active and that is the of two kinase domains that the active c-Kit kinase domain structure the kinase that is resistant to by and the design of specific and c-Kit kinase Receptor protein-tyrosine kinases (RPTKs) 1The abbreviations used are: RPTK, receptor protein-tyrosine kinase; SCF, stem cell factor; LC, liquid chromatography; MS, mass spectrometry; MES, 2[N-morpholinoethanesulfonic acid; PTR, phosphotyrosine.1The abbreviations used are: RPTK, receptor protein-tyrosine kinase; SCF, stem cell factor; LC, liquid chromatography; MS, mass spectrometry; MES, 2[N-morpholinoethanesulfonic acid; PTR, phosphotyrosine. regulate key signal transduction cascades that control cellular growth and proliferation. The stem cell factor (SCF) receptor c-Kit is a type III transmembrane RPTK comprised of five extracellular immunoglobulin domains, a single transmembrane region, an inhibitory cytoplasmic juxtamembrane domain, and a split cytoplasmic kinase domain separated by a kinase insert segment (1Yarden Y. Escobedo J.A. Kuang W.-J. Yang-Feng T.L. Daniel T.O. Tremble P.M. Chen E.Y. Ando M.E. Harkins R.N. Francke U. Fried V.A. Ullrich A. Williams L.T. Nature. 1986; 323: 226-232Crossref PubMed Scopus (764) Google Scholar, 2Ullrich A. Schlessinger J. Cell. 1990; 61: 203-212Abstract Full Text PDF PubMed Scopus (4583) Google Scholar). The type III RPTK family includes c-Kit (3Yarden Y. Kuang W.-J. Yang-Feng T. Coussens L. Munemitsu S. Dull T.J. Chen E. Schlessinger J. Francke U. Ullrich A. EMBO J. 1987; 6: 3341-3351Crossref PubMed Scopus (1317) Google Scholar), the colonystimulating factor-1 (formerly FMS) (4Coussens L. Van Beveren C. Smith D. Chen E. Mitchell R.L. Isacke C.M. Verma I.M. Ullrich A. Nature. 1986; 320: 277-280Crossref PubMed Scopus (289) Google Scholar), the platelet-derived growth factor α and β receptors (1Yarden Y. Escobedo J.A. Kuang W.-J. Yang-Feng T.L. Daniel T.O. Tremble P.M. Chen E.Y. Ando M.E. Harkins R.N. Francke U. Fried V.A. Ullrich A. Williams L.T. Nature. 1986; 323: 226-232Crossref PubMed Scopus (764) Google Scholar, 5Claesson-Welsh L. Eriksson A. Westermark B. Heldin C.-H. Proc. Natl. Acad. Sci. U. S. A. 1989; 86: 4917-4921Crossref PubMed Scopus (307) Google Scholar), and the FMS-related receptor FLT-3 (6Rosnet O. Schiff C. Pebusque M.-J. Marchetto S. Tonnelle C. Toiron Y. Birg F. Birnbaum D. Blood. 1993; 82: 1110-1119Crossref PubMed Google Scholar). Signaling by RPTKs occurs via ligand binding to the extracellular IG domains, inducing the receptors to form dimers, and thereby activating intrinsic tyrosine kinase activity through the transphosphorylation of specific tyrosine residues in the juxtamembrane and kinase domains (7Heldin C.-H. Cell. 1995; 80: 213-223Abstract Full Text PDF PubMed Scopus (1427) Google Scholar, 8Weiss A. Schlessinger J. Cell. 1998; 94: 277-280Abstract Full Text Full Text PDF PubMed Scopus (338) Google Scholar). Ligand binding both activates kinase activity and creates tyrosine-phosphorylated receptors that mediate the specific binding of intracellular signaling proteins. Src homology 2 and protein tyrosine binding domains (9Blume-Jensen P. Hunter T. Nature. 2001; 411: 355-365Crossref PubMed Scopus (3099) Google Scholar), including the protein-tyrosine phosphatase SHP-1, act as negative regulators of c-Kit activity (10Kozlowski M. Larose L. Lee F. Le D.M. Rottapel R. Siminovitch K.A. Mol. Cell. Biol. 1998; 18: 2089-2099Crossref PubMed Scopus (176) Google Scholar). These cytoplasmic signaling proteins initiate serine/threonine phosphorylation cascades that activate transcription factors to determine specific cellular responses (Fig. The human c-Kit gene is the cellular homologue of the v-kit oncogene found in the transforming Hardy-Zuckerman 4 feline sarcoma virus (11Snyder Jr., H.W. Broudeur D. Zuckerman E.E. Hardy W.D. Nature. 1986; 320: 415-421Crossref PubMed Scopus (450) Google Scholar) and encodes a 976-amino acid residue RPTK. Loss-of-function c-Kit mutations establish its importance for the normal growth of hematopoietic progenitor cells, mast cells, melanocytes, primordial germ cells, and the interstitial cells of Cajal (12Besmer P. Curr. Opin. Cell Biol. 1991; 3: 939-946Crossref PubMed Scopus (152) Google Scholar, 13Lyman S.D. Jacobsen S.E.W. Blood. 1998; 91: 1101-1134Crossref PubMed Google Scholar, 14Ashman L.K. Int. J. Biochem. Cell Biol. 1999; 31: 1037-1051Crossref PubMed Scopus (475) Google Scholar, 15Kitamura Y. Hirota S. Nishida T. Mutat. Res. 2001; 477: 165-171Crossref PubMed Scopus (60) Google Scholar). Gain-of-function mutations, resulting in SCF-independent, constitutive activation of c-Kit, are found in several highly malignant cancers. Mutations in the c-Kit juxtamembrane region cluster around the two main autophosphorylation sites that mediate protein tyrosine binding, Tyr-568 and Tyr-570, and are associated with human gastrointestinal stromal tumors (16Hirota S. Isozaki K. Moriyama Y. Hashimoto K. Nishida T. Ishiguro S. Kawano K. Hanada M. Kurata A. Takeda M. Tunio G.M. Matsuzawa Y. Kanakura Y. Sinomura Y. Kitamura Y. Science. 1998; 279: 577-580Crossref PubMed Scopus (3789) Google Scholar, 17Hirota S. M. Hashimoto K. Isozaki K. Kanakura Y. T. A. Kitamura Y. Nishida T. 1998; PubMed Scopus Google Scholar). Mutations in the kinase domain are found in mast cell and Y. Hirota S. Nishida T. Mutat. Res. 2001; 477: 165-171Crossref PubMed Scopus (60) Google Scholar) and in human germ cell tumors Jr., J. 1999; Full Text Full Text PDF PubMed Scopus Google Scholar). These mutations cells through c-Kit dimer two c-Kit kinases into to to act as and for (9Blume-Jensen P. Hunter T. Nature. 2001; 411: 355-365Crossref PubMed Scopus (3099) Google Scholar, M. Schlessinger J. J. Biol. 1998; Full Text Full Text PDF PubMed Scopus Google Scholar). The juxtamembrane domain c-Kit the binding of resulting in autophosphorylation and kinase The transforming kinase domain the active of the c-Kit activation mutations in residues in the and growth factor receptors are highly in ligand J. D.M. PubMed Scopus Google Scholar, Mol. Cell. Biol. PubMed Scopus Google Scholar) and are in and M. L. T. B. Proc. Natl. Acad. Sci. U. S. A. 94: PubMed Scopus Google Scholar, R. 1995; PubMed Scopus Google Scholar). of mutant c-Kit RPTKs in human the targeting of the c-Kit kinase domain for The of by the and in the of myelogenous is on the of the is in normal the kinase structure with the kinase the binding sites for T. P. B. J. Science. PubMed Scopus Google Scholar). an for human including gastrointestinal stromal tumors and of c-Kit with activating mutations in the juxtamembrane is in with activating mutations in the c-Kit kinase domain Y. P. F. S. J. M. A. K. C. Y. M. O. M. O. P. PubMed Scopus Google Scholar). We report on the and the crystal structure of a c-Kit complex. These results provide the molecular basis for the of c-Kit kinase transactivation and is an for the design of specific c-Kit kinase and domain of the human gene (4Coussens L. Van Beveren C. Smith D. Chen E. Mitchell R.L. Isacke C.M. Verma I.M. Ullrich A. Nature. 1986; 320: 277-280Crossref PubMed Scopus (289) Google by a and into the and sites of to a the and The kinase domain residues and with c-Kit protein with a by an in of cells and c-Kit protein a of of cell and by binding to and with to and c-Kit protein with The with and by a The c-Kit protein as by mass and to in in liquid and by autophosphorylation by of and and with and the a in for a used to and the a and split to with the and on a protein used to the phosphorylation sites on the and of c-Kit kinase by active with and and by of protein and of MES, in with and by in liquid the and and Scopus Google Scholar). The to the a and and two in the and structure are in The structure by molecular J. A. Scopus Google Scholar) with the receptor kinase used as a The the in the and The in Biol. PubMed Scopus Google Scholar) and and J. Biol. 1999; PubMed Scopus Google Scholar). The with the and is the of for of in are for the is the of for of in are for the in a new and domain of the human gene (4Coussens L. Van Beveren C. Smith D. Chen E. Mitchell R.L. Isacke C.M. Verma I.M. Ullrich A. Nature. 1986; 320: 277-280Crossref PubMed Scopus (289) Google by a and into the and sites of to a the and The kinase domain residues and with c-Kit protein with a by an in of cells and c-Kit protein a of of cell and by binding to and with to and c-Kit protein with The with and by a The c-Kit protein as by mass and to in in liquid and by autophosphorylation by of and and with and the a in for a used to and the a and split to with the and on a protein used to the phosphorylation sites on the and of c-Kit kinase by active with and and by of protein and of MES, in with and by in liquid the and and Scopus Google Scholar). The to the a and and two in the and structure are in The structure by molecular J. A. Scopus Google Scholar) with the receptor kinase used as a The the in the and The in Biol. PubMed Scopus Google Scholar) and and J. Biol. 1999; PubMed Scopus Google Scholar). The with the the phosphorylation with the the the mass to to the of the The for the the of a of and to the (Fig. The and the phosphorylation sites to Tyr-568 and and structure of active c-Kit kinase is of and of the of an active kinase (Fig. The is and for the active and for of the structure and loops. of the residues in both in the are the of the of main and a of both is The acid residues of both are as are the residues the kinase The of both the and forms a key of the active are with an active kinase structure (Fig. of active c-Kit The the kinase and key including the phosphate-binding and kinase activation The of the and are of c-Kit kinase the protein serine/threonine kinase with a comprised of and a (Fig. The a single the control the and binding and kinase activity in The c-Kit is in a with The forms a with the of and the to the and of the The is in an active state with binding a that the and and the of an (Fig. c-Kit active the c-Kit active with and are and c-Kit active around the and in the the and the into a with the and to the and of the region residues and (Fig. The and the forms a with the The of the with the residue of the c-Kit The residues the with the active to the transphosphorylation (Fig. c-Kit kinase active is fully for autophosphorylation as by the of both residues the and in the These in the in by the of the and of the and with the of the III RPTK the tyrosine residues are to the kinase domain and the of the is for the to the autophosphorylation in of the is by a and and by and with residues the of the binding the active of the kinase the that the is of the that the c-Kit is in a active is of the of the residue with the of in the The of the on residues the negative of a and the in an active the phosphorylation with the the the mass to to the of the The for the the of a of and to the (Fig. The and the phosphorylation sites to Tyr-568 and and structure of active c-Kit kinase is of and of the of an active kinase (Fig. The is and for the active and for of the structure and loops. of the residues in both in the are the of the of main and a of both is The acid residues of both are as are the residues the kinase The of both the and forms a key of the active are with an active kinase structure (Fig. The of c-Kit kinase the protein serine/threonine kinase with a comprised of and a (Fig. The a single the control the and binding and kinase activity in The c-Kit is in a with The forms a with the of and the to the and of the The is in an active state with binding a that the and and the of an (Fig. and c-Kit active around the and in the the and the into a with the and to the and of the region residues and (Fig. The and the forms a with the The of the with the residue of the c-Kit The residues the with the active to the transphosphorylation (Fig. The c-Kit kinase active is fully for autophosphorylation as by the of both residues the and in the These in the in by the of the and of the and with the of the III RPTK the tyrosine residues are to the kinase domain and the of the is for the to the autophosphorylation in of the is by a and and by and with residues the of the binding the active of the kinase the that the is of the that the c-Kit is in a active is of the of the residue with the of in the The of the on residues the negative of a and the in an active in c-Kit the of its constitutive activation in the normal state c-Kit receptor as a in the cell of induces the c-Kit receptor to as both and for c-Kit autophosphorylates specific tyrosine residues in protein kinases are and cellular residues are the signal that activates intracellular serine/threonine protein kinase signaling cascades to determine specific cellular responses in normal cellular growth and (Fig. We and the crystal structure of active c-Kit kinase to an of the molecular basis by activating c-Kit We autophosphorylation with a c-Kit that the tyrosine c-Kit to the Tyr-568 and are and two residues are the to are of and that the residue is the tyrosine residue to by the crystal structure of the active c-Kit in the is ordered and in an active phosphorylation of is to activate the These results are in with for kinases in phosphorylation of residues is to the kinase in an active state in M. J. Cell. Full Text Full Text PDF PubMed Scopus Google Scholar). in normal c-Kit receptor protein-tyrosine the kinase domain its active and that is the of two kinase domains that the active c-Kit kinase domain structure the kinase that is resistant to by and the design of specific and c-Kit kinase in c-Kit the of its constitutive activation in the normal state c-Kit receptor as a in the cell of induces the c-Kit receptor to as both and for c-Kit autophosphorylates specific tyrosine residues in protein kinases are and cellular residues are the signal that activates intracellular serine/threonine protein kinase signaling cascades to determine specific cellular responses in normal cellular growth and (Fig. We and the crystal structure of active c-Kit kinase to an of the molecular basis by activating c-Kit We autophosphorylation with a c-Kit that the tyrosine c-Kit to the Tyr-568 and are and two residues are the to are of and that the residue is the tyrosine residue to by the crystal structure of the active c-Kit in the is ordered and in an active phosphorylation of is to activate the These results are in with for kinases in phosphorylation of residues is to the kinase in an active state in M. J. Cell. Full Text Full Text PDF PubMed Scopus Google Scholar). in normal c-Kit receptor protein-tyrosine the kinase domain its active and that is the of two kinase domains that the active c-Kit kinase domain structure the kinase that is resistant to by and the design of specific and c-Kit kinase We J. for protein M. for protein A. for mass D. for and for We the is by the of of of the of