Expression cloning of the human IL-3 receptor cDNA reveals a shared beta subunit for the human IL-3 and GM-CSF receptors.
A cDNA for a human interleukin-3 (hIL-3) binding protein has been isolated by a novel expression cloning strategy: a cDNA library was coexpressed with the cDNA for the beta subunit of human granulocyte/macrophage colony-stimulating factor (GM-CSF) receptor (hGMR beta) in COS7 cells and screened by binding of 125I-labeled IL-3. The cloned cDNA (DUK-1) encodes a mature protein of 70 kd, which belongs to the cytokine receptor family and which alone binds hIL-3 with extremely low affinity (Kd = 120 +/- 60 nM). A high affinity IL-3-binding site (Kd = 140 +/- 30 pM) was reconstituted by coexpressing the DUK-1 protein and hGMR beta, indicating that hIL-3R and hGMR share the beta subunit. Therefore, we designated DUK-1 as the alpha subunit of the hIL-3R. As in human hematopoietic cells, hIL-3 and hGM-CSF complete for binding in fibroblasts expressing the cDNAs for hIL-3R alpha, GMR alpha, and the common beta subunit, indicating that different alpha subunits compete for a common beta subunit.
Kitamura
T
T
Department of Molecular Biology, DNAX Research Institute of Molecular and Cellular Biology, Palo Alto, California 94304.
Sato
N
N
Arai
K
K
Miyajima
A
A
D000595:Amino Acid Sequence; D001483:Base Sequence; D001667:Binding, Competitive; D015152:Blotting, Northern; D003001:Cloning, Molecular; D003432:Cross-Linking Reagents; D004247:DNA / Q000235:genetics; D015870:Gene Expression; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000378:metabolism; D006801:Humans; D007377:Interleukin-3 / Q000378:metabolism; D007378:Interleukins / Q000378:metabolism; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D015394:Molecular Structure; D012333:RNA, Messenger / Q000235:genetics; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor / Q000737:chemistry / Q000235:genetics*; D016185:Receptors, Interleukin-3 / Q000737:chemistry / Q000235:genetics*; D011994:Recombinant Proteins
D003432:Cross-Linking Reagents; D007377:Interleukin-3; D007378:Interleukins; D046911:Macromolecular Substances; D012333:RNA, Messenger; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor; D016185:Receptors, Interleukin-3; D011994:Recombinant Proteins; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D004247:DNA