Molecular cloning of a novel type 1 cytokine receptor similar to the common gamma chain

In a complementary DNA (cDNA) screening of murine Th2-skewed lymphocytes wi th our recently developed signal sequence trap method termed SST-REX, a nov el type 1 cytokine receptor, Delta1 (delta 1), was identified. Although del ta 1 is ubiquitously expressed in multiple tissues, the expression level is higher in Th2-skewed lymphocytes than in Th1-skewed ones. The delta 1 cDNA encodes a 359-amino acid type I membrane protein. The extracellular domain of 206 amino acids showed 24% identity with the murine common gamma recept or that is shared among the receptors for interleukin(IL)-2, IL-4, IL-7, IL -9, and IL-15. The membrane-proximal region of delta 1 includes a box1 moti f, which is important for association with Janus kinases (JAKs), and showed a significant homology with that of the mouse erythropoietin receptor (EPO R). A box2 motif was also found in close proximity to the box1 region. Dime rization of the cytoplasmic region of delta 1 alone did not transduce proli ferative signals in IL-3-dependent cell lines, However, the membrane-proxim al region of delta 1 could substitute for that of human EPOR in transmittin g proliferative signals and activating JAK2. These results suggest that del ta 1 is a subunit of cytokine receptor that may be involved in multiple rec eptor systems and play a regulatory role in the immune system and hematopoi esis, (Blood, 2000; 95:2204-2211) (C) 2000 by The American Society of Hemat ology.