Molecular cloning and characterization of CRLM-2, a novel type I cytokine receptor preferentially expressed in hematopoietic cells

A murine expressed sequence tag (EST) showing homology with erythropoietin receptor (EPOR) was identified in the EST database. Cloning of the full-length cDNA revealed a 359 amino acid novel type I cytokine receptor, designated cytokine receptor like molecule-2 (CRLM-2). While CRLM-2 lacks typical WSXWS motif, it has a significant homology with EPOR, IL-2 receptor beta and gamma, and IL-9 receptor alpha. The murine CRLM-2 gene is composed of 8 exons, and an alternative mRNA splicing generates a variant transcript encoding a soluble CRLM-2. CRLM-2 is preferentially expressed in hematopoietic cells, particularly in hematopoietic progenitors and myeloid cells. Furthermore, CRLM-2 is constitutively associated with JAK2, a well-known tyrosine kinase that transmits signals from cytokine receptors. These data strongly suggest that CRLM-2 is a novel cytokine receptor involved in the regulation of hematopoietic system.