Plays an important role in the immune response against parasites by acting as a receptor of IL9. Interacts with IL9. The WSXWS motif appears to be necessary for proper protein folding and thereby efficient intracellular transport and cell-surface receptor binding. The box 1 motif is required for JAK interaction and/or activation. The gene coding for this protein is located in the pseudoautosomal region 2 (PAR2) of X and Y chromosomes. Belongs to the type I cytokine receptor family. Type 4 subfamily. Extended N-terminus.