STRUCTURE OF THE ERYTHROPOIETIN RECEPTOR

Despite extensive studies, the structure of the erythropoietin recepto r remains little understood. cDNAs encoding the human and murine eryth ropoietin receptors have been cloned and the structure of these protei ns is discussed. Although the proteins encoded by these cDNAs play key roles in erythropoietin binding and in erythropoietin signal transduc tion, increasing evidence strongly suggests that the erythropoietin re ceptor is a multimeric complex. The murine erythropoietin receptor has been solubilized under mild conditions and the molecular mass of the native receptor has been shown to be significantly higher than the mol ecular mass of the cloned chain. Cross-linking experiments have reveal ed the presence of three proteins covalently bound to erythropoietin b y the cross-linking reagents; however, only one of them seems to deriv e from the cloned chain. Moreover, functional evidence also suggests t he presence of other erythropoietin receptor subunits.