Fig. 6.

Multiple sequence alignments of IL-31, IL-31RA and OSMRβ from different species. a Sequence alignments of mature IL-31 proteins from canine, feline and human were performed with the CLC Sequence Viewer and the Lasergene DNASTAR Megalign program. Four alpha-helices, αA, αB, αC and αD, are marked with squares in the colors of marine, green, yellow, and magenta, respectively. The amino acids, E21, E83, H87, and K111 of hIL-31, which were proved to be decisive positions in the interaction with its receptors, were emphasized with black edged boxes (Le Saux et al. 2010). The binding sites of fIL-31 to fOSMRβ, G38 and the “PADNFERK” (P104-K111) motif are framed with the green dashed line. Whereas, the overlapping binding site of fIL-31 to both fIL-31RA and fOSMRβ is in the frame of the blue dashed line (Medina-Cucurella et al. 2020). b Protein sequence alignment of cytokine-binding domains (CBD) of IL-31RA from three species. c The first four domains, including one Ig-like domain and three CBDs of OSMRβ were aligned by the Clustal W method using the Lasergene Megalign program. d Percentage identity matrix obtained with Clustal W alignments of IL-31, IL-31RA and OSMRβ from canine, feline, and human