The expression of functional erythropoietin receptors on an interleukin-3 dependent cell line

We report the expression of the erythropoietin receptors on an interleukin-3 dependent cell line. By the transfer into medium supplemented with erythropoietin, DA-1 cells were converted to an erythropoietin dependent growth state. [125I] erythropoietin was used to detect receptors specific for this hormone on the cell surface. Binding studies revealed that erythropoietin bound to 131 +/- 23 receptors/cell with a Kd of 0.54 +/- 0.2 nM. When the cells were incubated at 37 degrees C, trichloroacetic acid soluble radioactivity appeared in the medium after [125I] erythropoietin binding began to decrease, suggesting that the decline represents the degradation of cell associated [125I] erythropoietin- receptor complexes.