Receptor for erythropoietin. Mediates erythropoietin-induced erythroblast proliferation and differentiation. Expressed in the ventral blood island from stage 28 through to stage 36. Expressed in the circulating blood by stage 40. In the adult, highly expressed in peripheral blood cells including immature erythrocytes and basophils, and moderately expressed in the hematopoietic organs: liver, kidney and spleen. Expressed at a low level in adult brain. First expressed at a low level at stage 18 (late neurula), with high levels of expression seen from stage 32 through to stage 48 (tadpole). 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. Contains 1 copy of a cytoplasmic motif that is referred to as the immunoreceptor tyrosine-based inhibitor motif (ITIM). This motif is involved in modulation of cellular responses. The phosphorylated ITIM motif can bind the SH2 domain of several SH2-containing phosphatases (By similarity). Belongs to the type I cytokine receptor family. Type 1 subfamily.