Isoforms of human and mouse IL-31RA. S, signal peptide; CBD, cytokine-binding domain; FnIII, fibronectin type III; TMD, transmembrane domain; Box1/2, cytoplasmic box 1 and box 2 signaling motifs; Y, location of tyrosine in the cytoplasmic domain. GLM-R and IL-31RAV3 are exactly the same. GPL745 differs from GLM-R only at the signal peptide region with GPL745 shorter for 19 aa. IL-31RAv4 starts at the same aa with CRL3 and GP745. GenBank accession numbers: IL-31RAv1, AY499339; IL-31RAv2, AY499340; IL-31RAv3, AY499341; IL-31RAv4, AY499342; GLM-R, NM_139017; CRL3, AF106913; mIL-31RAv1, AY509150; mIL-31RAv2, AY509151.