Ligand-induced association of the type I interferon receptor components.
Two transmembrane polypeptides, IFNAR and IFN-alpha/Beta R, were previously identified as essential components of the type I interferon (IFN) receptor, but their interrelationship and role in ligand binding were not clear. To study these issues, we stably expressed and characterized the two polypeptides in host murine cells. In human cells, native IFN-alpha/beta R is a 102-kDa protein but upon reduction only a 51-kDa protein is detected. In host murine cells human IFN-alpha/beta R was expressed as a 51-kDa protein. Host cells expressing IFN-alpha/beta R bound IFN-alpha 2 with a high affinity (Kd of 3.6 nM), whereas cells expressing IFNAR exhibited no ligand binding. Upon coexpression of IFNAR and the 51-kDa IFN-alpha/beta R, the affinity for IFN-alpha 2 was increased 10-fold, approaching that of the native receptor. We show by cross-linking that both the cloned (51-kDa) and native (102-kDa) IFN-alpha/beta R bind IFN-alpha 2 to form an intermediate product, while IFNAR associates with this product to form a ternary complex. Hence, IFNAR and IFN-alpha/beta R are components of a common type I IFN receptor, cooperating in ligand binding. Ligand-induced association of IFNAR and IFN-alpha/beta R probably triggers transmembrane signaling.
Cohen
B
B
Department of Molecular Genetics and Virology, Weizmann Institute of Science, Rehovot, Israel.
Novick
D
D
Barak
S
S
Rubinstein
M
M
D016475:3T3 Cells; D000818:Animals; D001483:Base Sequence; D003432:Cross-Linking Reagents; D006801:Humans; D000077190:Interferon alpha-2; D016898:Interferon-alpha / Q000494:pharmacology*; D008024:Ligands; D008565:Membrane Proteins; D051379:Mice; D008969:Molecular Sequence Data; D011233:Precipitin Tests; D011485:Protein Binding; D053633:Receptor, Interferon alpha-beta; D017471:Receptors, Interferon / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000187:drug effects / Q000378:metabolism
D003432:Cross-Linking Reagents; C507964:IFNAR1 protein, human; D000077190:Interferon alpha-2; D016898:Interferon-alpha; D008024:Ligands; D008565:Membrane Proteins; D017471:Receptors, Interferon; D011994:Recombinant Proteins; D053633:Receptor, Interferon alpha-beta