title: Identification of IFN-gamma receptor binding sites for JAK2 and enhancement of binding by IFN-gamma and its C-terminal peptide IFN-gamma(95-133).
abstract: The tyrosine kinase JAK2 is an integral part of the signal transduction pathways of a number of cytokines and growth factors, including IFN-gamma. Previously, we identified a species-nonspecific binding site for the C terminus of IFN-gamma, encompassed by IFN-gamma peptide IFN-gamma(95-133), on the membrane proximal region of the cytoplasmic domain of the IFN-gamma R alpha-chain. Using both a radioligand binding assay and coimmunoprecipitation with antireceptor antiserum, we were able to demonstrate specific interaction of JAK2 with the murine IFN-gamma R(MIR) alpha-chain. Furthermore, this interaction is increased by the addition of murine IFN-gamma or its C-terminal peptide, muIFN-gamma(95-133). We also identified two regions of the cytoplasmic domain of the receptor that interact with JAK2 using synthetic peptides of the MIR alpha-chain in receptor competition studies. These regions are encompassed by receptor peptide MIR(283-309), which is adjacent to the membrane proximal region at which the C terminus of IFN-gamma binds, and receptor peptide MIR(404-432), which lies near the C terminus of the receptor, encompassing a potentially important phosphorylation site. These data show site-specific interaction between JAK2 and IFN-gamma with the IFN-gamma R and have broader implications for the role of the IFN-gamma ligand in the IFN-gamma signal transduction pathway. Furthermore, the data support previous studies that demonstrated that intracellular IFN-gamma plays a role in cell activation.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002478:Cells, Cultured; D007371:Interferon-gamma / Q000494:pharmacology*; D053614:Janus Kinase 2; D051379:Mice; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000494:pharmacology; D011485:Protein Binding / Q000187:drug effects; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins; D017471:Receptors, Interferon / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D010446:Peptide Fragments; D011518:Proto-Oncogene Proteins; D017471:Receptors, Interferon; D011994:Recombinant Proteins; D007371:Interferon-gamma; D011505:Protein-Tyrosine Kinases; C507926:Jak2 protein, mouse; D053614:Janus Kinase 2