title: The MATK tyrosine kinase interacts in a specific and SH2-dependent manner with c-Kit.
abstract: We have cloned a protein tyrosine kinase, MATK, which is expressed abundantly in megakaryocytes and the brain. We investigated whether MATK participates in the c-Kit ligand/stem cell factor (KL/SCF) signaling pathway in the megakaryocytic cell line CMK. After KL/SCF stimulation, five major proteins of molecular masses of 145, 113, 92, 76, and 63 kDa were rapidly and transiently tyrosine-phosphorylated in a time-dependent manner, peaking within 5 min, and returning to basal levels within 60 min. To study the role of MATK in the KL/SCF signaling pathway, glutathione S-transferase (GST) fusion proteins containing SH2 and SH3 domains of MATK were cloned, expressed in Escherichia coli, and purified. MATK-SH2, but not MATK-SH3, precipitated the tyrosine-phosphorylated c-Kit (molecular mass of 145 kDa) in KL/SCF-stimulated CMK cells. Other GST fusion proteins containing the SH2 domain of p85 of phosphatidylinositol 3-kinase, phospholipase C gamma-1, and ras-GAP also precipitated c-Kit. The tyrosine-phosphorylated c-Kit was co-immunoprecipitated with anti-MATK and anti-p85 antibodies in KL/SCF-stimulated CMK cells, but not in granulocyte-macrophage colony stimulating factor or interleukin-6-stimulated cells, suggesting receptor specificity. These results indicate that MATK associates with the c-Kit receptor following specific stimulation by KL/SCF via its SH2 domain and likely participates in transduction of growth signals induced by this cytokine in megakaryocytes.
authors.affiliation: Department of Medicine, Deaconess Hospital, Harvard Medical School, Boston, Massachusetts 02215, USA.
authors.forename: B H
authors.initials: BH
authors.lastname: Jhun
authors.forename: B
authors.initials: B
authors.lastname: Rivnay
authors.forename: D
authors.initials: D
authors.lastname: Price
authors.forename: H
authors.initials: H
authors.lastname: Avraham
mesh_terms: D020690:GTPase-Activating Proteins; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D016298:Hematopoietic Cell Growth Factors / Q000494:pharmacology; D006801:Humans; D015850:Interleukin-6 / Q000494:pharmacology; D008533:Megakaryocytes / Q000201:enzymology*; D011505:Protein-Tyrosine Kinases / Q000502:physiology*; D011506:Proteins / Q000502:physiology; D011518:Proto-Oncogene Proteins / Q000502:physiology*; D019009:Proto-Oncogene Proteins c-kit; D016392:Proto-Oncogene Proteins pp60(c-src); D020794:Receptor Protein-Tyrosine Kinases / Q000502:physiology*; D016184:Receptors, Colony-Stimulating Factor / Q000502:physiology*; D019089:Stem Cell Factor; D020703:ras GTPase-Activating Proteins
chemical_list: D020690:GTPase-Activating Proteins; D016298:Hematopoietic Cell Growth Factors; D015850:Interleukin-6; D011506:Proteins; D011518:Proto-Oncogene Proteins; D016184:Receptors, Colony-Stimulating Factor; D019089:Stem Cell Factor; D020703:ras GTPase-Activating Proteins; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D011505:Protein-Tyrosine Kinases; D019009:Proto-Oncogene Proteins c-kit; D020794:Receptor Protein-Tyrosine Kinases; C085377:MATK protein, human; D016392:Proto-Oncogene Proteins pp60(c-src)