Receptor for thymic stromal lymphopoietin (TSLP). Forms a functional complex with TSLP and IL7R which is capable of stimulating cell proliferation through activation of STAT3 and STAT5 (By similarity). Also activates JAK2 (By similarity). Implicated in the development of the hematopoietic system. Heterodimer of CRLF2 and IL7R. Expressed in all tissues examined including brain, thymus, lung, heart, muscle, stomach, small intestine, liver, kidney, spleen, testis and skin. Highest levels in thymus, liver and testis. 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. Belongs to the type I cytokine receptor family. Type 5 subfamily.