p135tyk2, an interferon-alpha-activated tyrosine kinase, is physically associated with an interferon-alpha receptor.
Recent genetic studies have linked the tyk2 gene, which encodes a novel type of non-receptor tyrosine kinase, to the interferon-alpha intracellular signaling pathway. In this report, biochemical evidence is presented which supports this proposed function for the tyk2 tyrosine kinase and further defines its role in the interferon-alpha signaling cascade. Specifically, the tyk2 gene is shown to encode a 135-kDa protein which is rapidly phosphorylated on tyrosine in response to interferon-alpha treatment. Indirect evidence suggests that the tyrosine phosphorylation of p135tyk2 is the result of autokinase activity, implying that the Tyk2 tyrosine kinase is activated by interferon-alpha treatment. Two complementary methods demonstrate a physical association between p135tyk2 and the alpha-subunit of the interferon-alpha receptor. First, immunoblots show that monoclonal antibodies against the alpha-subunit of the interferon-alpha receptor can co-immunoprecipitate p135tyk2. Second, interferon-alpha receptor proteins which have been labeled by affinity cross-linking with 125I-interferon-alpha 2 can be co-immunoprecipitated using anti-tyk2 antisera. Taken together, these data suggest that an interferon-alpha receptor-p135tyk2 complex functions, in a manner analogous to the CD4-lck tyrosine kinase complex, to initiate the interferon-alpha signaling cascade.
Colamonici
O R
OR
Department of Pathology, University of Tennessee, Memphis 38163.
Uyttendaele
H
H
Domanski
P
P
Yan
H
H
Krolewski
J J
JJ
D000818:Animals; D000911:Antibodies, Monoclonal; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D017931:DNA Primers; D018076:DNA, Complementary / Q000378:metabolism; D004789:Enzyme Activation; D015870:Gene Expression; D006367:HeLa Cells; D006801:Humans; D015151:Immunoblotting; D016898:Interferon-alpha / Q000378:metabolism / Q000494:pharmacology*; D008969:Molecular Sequence Data; D009036:Moths; D014176:Protein Biosynthesis; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011506:Proteins / Q000302:isolation & purification / Q000378:metabolism*; D053633:Receptor, Interferon alpha-beta; D017471:Receptors, Interferon / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000378:metabolism; D015398:Signal Transduction; D053634:TYK2 Kinase; D014162:Transfection
D000911:Antibodies, Monoclonal; D017931:DNA Primers; D018076:DNA, Complementary; D016898:Interferon-alpha; D011506:Proteins; D017471:Receptors, Interferon; D011993:Recombinant Fusion Proteins; D053633:Receptor, Interferon alpha-beta; D011505:Protein-Tyrosine Kinases; D053634:TYK2 Kinase; C070139:TYK2 protein, human