Tyrosine phosphorylation of the alpha and beta subunits of the type I interferon receptor. Interferon-beta selectively induces tyrosine phosphorylation of an alpha subunit-associated protein.
We studied the phosphorylation of the alpha and beta subunits of the Type I interferon (IFN) receptor induced by Type I IFNs in the human U-266 and MOLT-4 cell lines. Both IFN-alpha and IFN-beta induced tyrosine phosphorylation of the beta subunit of the receptor. The Type I IFN-induced tyrosine phosphorylation of the beta subunit was rapid and transient, being detectable within 1 min of Type I IFN treatment and gradually diminishing to almost base-line levels by 60 min. All Type I IFNs studied were found to induce tyrosine phosphorylation of the alpha subunit of the Type I IFN receptor, the p135tyk2 and JAK-1 tyrosine kinases, and the ISGF3 alpha components. Interestingly, IFN-beta, but not IFN-alpha or IFN-omega, induced tyrosine phosphorylation of an alpha subunit-associated protein with an apparent molecular mass of approximately 100 kDa (p100). These data suggest the existence of a common signaling pathway(s) for Type I IFNs involving the alpha and beta subunits of the receptor, the tyrosine kinases p135tyk2 and JAK-1, and the ISGF3 alpha components. However, differences between the signaling pathways of different Type I IFNs exist, as suggested by tyrosine phosphorylation of an alpha subunit-associated protein only in response to IFN-beta.
Department of Medicine, Loyola University of Chicago, Illinois.
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Platanias
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Uddin
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Colamonici
D006801:Humans; D016898:Interferon-alpha / Q000378:metabolism; D016899:Interferon-beta / Q000378:metabolism; D010766:Phosphorylation; D011506:Proteins / Q000378:metabolism; D017471:Receptors, Interferon / Q000737:chemistry / Q000378:metabolism*; D015398:Signal Transduction; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000378:metabolism*
D016898:Interferon-alpha; D011506:Proteins; D017471:Receptors, Interferon; D014443:Tyrosine; D016899:Interferon-beta