Differential tyrosine phosphorylation of the IFNAR chain of the type I interferon receptor and of an associated surface protein in response to IFN-alpha and IFN-beta.
The human interferon alpha-receptor (IFNAR gene product) is a transmembranal protein of 557 amino acids with an intracytoplasmic domain of 100 amino acids containing four tyrosines. Antibodies to a C-terminal peptide (residues 521-536) were developed which efficiently immunoprecipitate the 105 kDa IFNAR protein from detergent extracts of human cells. We show that the IFNAR protein becomes tyrosine phosphorylated within 5 min after treatment of human myeloma U266 cells with IFN-alpha 2, IFN-alpha 8 or IFN-beta. The IFNAR chain interacts with both IFN-alpha 2 and IFN-beta, as demonstrated by cross-linking. Among elements involved in signal transduction by type I IFNs, the tyrosine kinase Tyk2 but not Jak1, and the ISGF3 transcription factor subunit Stat2 (p113) but not Stat1 (p91), are found associated with the IFNAR protein. After IFN-beta treatment for 5 min, a tyrosine-phosphorylated protein of approximately 95 kDa (beta-PTyr) is found bound to IFNAR, but can be dissociated by denaturation. The beta-PTyr protein is present on the cell surface, like IFNAR, as shown by extracellular biotin tagging. The ratio of beta-PTyr to IFNAR tyrosine phosphorylation is much higher with IFN-beta than with IFN-alpha 2 or 8. Both are IFN dependent and abrogated by a monoclonal antibody which blocks IFNAR action. The beta-PTyr component may represent an important difference in the action of IFN-beta as compared with IFN-alpha in their shared receptor system.
Abramovich
C
C
Department of Molecular Genetics and Virology, Weizmann Institute of Science, Rehovot, Israel.
Shulman
L M
LM
Ratovitski
E
E
Harroch
S
S
Tovey
M
M
Eid
P
P
Revel
M
M
D000595:Amino Acid Sequence; D004268:DNA-Binding Proteins / Q000378:metabolism; D006801:Humans; D050832:Interferon-Stimulated Gene Factor 3; D050834:Interferon-Stimulated Gene Factor 3, gamma Subunit; D016898:Interferon-alpha / Q000494:pharmacology*; D016899:Interferon-beta / Q000494:pharmacology*; D053613:Janus Kinase 1; D008565:Membrane Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D009101:Multiple Myeloma / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D053633:Receptor, Interferon alpha-beta; D017471:Receptors, Interferon / Q000145:classification / Q000187:drug effects / Q000378:metabolism*; D015398:Signal Transduction; D053634:TYK2 Kinase; D014157:Transcription Factors / Q000378:metabolism; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000378:metabolism
D004268:DNA-Binding Proteins; C494227:IRF9 protein, human; D050832:Interferon-Stimulated Gene Factor 3; D050834:Interferon-Stimulated Gene Factor 3, gamma Subunit; D016898:Interferon-alpha; D008565:Membrane Proteins; D010750:Phosphoproteins; D011506:Proteins; D017471:Receptors, Interferon; D014157:Transcription Factors; D053633:Receptor, Interferon alpha-beta; D014443:Tyrosine; D016899:Interferon-beta; D011505:Protein-Tyrosine Kinases; C507904:JAK1 protein, human; D053613:Janus Kinase 1; D053634:TYK2 Kinase; C070139:TYK2 protein, human