IFNAR1

IFNAR1, one of the subunit of IFN-α/β receptor, is a type I IFN receptor. IFNAR1 forms the heterodimeric receptor (IFN-α/β receptor) with IFNAR2. IFNAR1 interacts with tyrosine kinase 2 (Tyk2), and the interaction is able to stabilize IFNAR1 on the plasma membrane[1]. Besides, IFNAR1 associates with TYK2 and initiates type I IFN-induced STAT signaling, but the activation needs IFNAR2 as a platform[2]. IFN-α/-β can induce association of the IFNAR1 and IFNAR2, which makes JAK1 and TYK2 form a functional signaling unit[1]. Upon activation by these IFNs, IFNAR1 and IFNAR2 undergo a conformational change to promote a cascade of downstream signaling events. The signaling events includes the phosphorylation of Tyk2 and JAK1, the signal transducers and activators of transcription STAT1 and STAT2, and the formation of the IFN-stimulated gene factor 3 (ISGF3) complex which consists of phosphorylated STAT1 and STAT2 and IRF9[3]. Human IFNAR1 consists of extracellular domain (K28-K436), helical domain (I437-A457), and cytoplasmic domain (K458-V557). Human IFNAR1 shares <50% aa sequence identity with mouse. IFNAR1 is expressed on peripheral blood B cells and monocytes, and mediates differentiation and activation of these cells[4].