Characterization of the erythropoietin receptor on a Friend murine erythroleukemic cell clone, TSA8
Kitamura, T.; Tojo, A.; Fukamachi, H.; Akahane, K.; Saito, T.; Urabe, A.; Takaku, F.
Nihon Ketsueki Gakkai Zasshi Journal of Japan Haematological Society 51(4): 677-685
1988
ISSN/ISBN: 0001-5806 PMID: 2849278 Document Number: 308093
We investigated the erythropoietin (EPO) receptor expressed on a Friend erythroleukemic cell clone, TSA8, using 125I-labeled human recombinant EPO. The binding of 125I-EPO was displaced by unlabeled EPO in a dose-dependent manner, but not by other growth factors nor various lymphokines, indicating the presence of specific binding sites for EPO. Scatchard analysis of the binding data suggested the existence of two classes of binding sites, one with high-affinity (Kd=0.25 .+-. 0.05 nM, 90 .+-. 20 sites/cell) and the other with low-affinity (Kd=6.1 .+-. 3.3 nM, 590 .+-. 230 sites/cell). We also investigated EPO binding to plasma membrane preparation of TSA8 cells and demonstrated the existence of two classes of EPO receptor with affinities similar to those examined in intact cells. By our method, recovery of 125I-EPO binding in plasma membrane preparations was between 70 and 100% of intact cells.