Cloning and Expression of a Long Form of the β Subunit of the Interferon αβ Receptor That Is Required for Signaling

The interferon αβ receptor (IFNαR) or type I IFN-R is formed by a 110-kDa α subunit or IFNAR and by a β subunit, which has short and long forms (molecular masses of 55 and 95-100 kDa, respectively). In this report, we demonstrate that the IFNα/βR cDNA recently cloned corresponds to the 55-kDa or short form of the β subunit, while the 95-100-kDa species reported here corresponds to a longer form of the IFNα/βR cDNA that is probably produced by alternative splicing of the same gene. Stable transfection of the α subunit with either form of the β subunit results in the expression of low and high affinity receptors, while expression of either form of the β subunit alone only produces low affinity receptors. More important, only expression of the α and long form of the human β subunits in mouse L-929 cells reconstitutes the activation of the Jak kinases and the Stat factors, as well as the antiviral response to human type I IFNs. The interferon αβ receptor (IFNαR) or type I IFN-R is formed by a 110-kDa α subunit or IFNAR and by a β subunit, which has short and long forms (molecular masses of 55 and 95-100 kDa, respectively). In this report, we demonstrate that the IFNα/βR cDNA recently cloned corresponds to the 55-kDa or short form of the β subunit, while the 95-100-kDa species reported here corresponds to a longer form of the IFNα/βR cDNA that is probably produced by alternative splicing of the same gene. Stable transfection of the α subunit with either form of the β subunit results in the expression of low and high affinity receptors, while expression of either form of the β subunit alone only produces low affinity receptors. More important, only expression of the α and long form of the human β subunits in mouse L-929 cells reconstitutes the activation of the Jak kinases and the Stat factors, as well as the antiviral response to human type I IFNs.