Identification of the erythropoietin receptors of erythroleukemic cells.
Erythropoietin (epo) is the physiologic regulator of red blood cell development. We have demonstrated the presence of epo receptors on two erythroleukemia cell lines, IW32 and IW201. IW32 produces epo constitutively while IW201 is a nonproducing cell line. Neither cell lines respond to epo to differentiate. In this study, we have shown that these cells bound 125I-epo specifically. Binding could be displaced by the presence of unlabeled epo but not by insulin or epidermal growth factor. In contrast to that found in epo responsive cells isolated from Friend virus infected mouse spleen, which were reported to contain both "high" and "low" affinity receptors, our finding indicated only a single class of "low" affinity receptors with apparent dissociation constants of 1.7 nM and 2.0 nM for IW32 and IW201 cell lines, respectively. It is suggested that the absence of "high" affinity receptors may account for the lack of responsiveness of these cells to epo.
Wang
F F
FF
Institute of Biochemistry, Yang-Ming Medical College, Taipei, Taiwan.
Wang
Y J
YJ
Lee
H J
HJ
Fong
J C
JC
D000818:Animals; D002460:Cell Line; D004921:Erythropoietin / Q000378:metabolism*; D007457:Iodine Radioisotopes; D007700:Kinetics; D004915:Leukemia, Erythroblastic, Acute / Q000378:metabolism*; D007942:Leukemia, Experimental / Q000378:metabolism*; D051379:Mice; D011956:Receptors, Cell Surface / Q000378:metabolism*; D017467:Receptors, Erythropoietin
D007457:Iodine Radioisotopes; D011956:Receptors, Cell Surface; D017467:Receptors, Erythropoietin; D004921:Erythropoietin