Erythropoietin Receptor Structural Domains.

Erythropoietin (EPO) is a hormone that is important for regulating red blood cell production. It is functional through binding to its receptor-EpoR. EpoR is a single-span membrane protein. It contains an extracellular region, a transmembrane domain, and a C-terminus. The extracellular region is important for binding to EPO, and its conformation is critical for signal transduction. The transmembrane domain contains 21 residues forming a helix which plays an important role in transferring ligand-induced conformational changes of the extracellular domain across the cell membrane. The C-terminal region contains the Janus kinase 2-binding sites and eight tyrosine residues that can be phosphorylated to become binding sites for transcription factors to active the downstream pathways. This chapter focuses on structural description of the domains of the EpoR. The recent progress in the structural determination of these domains is summarized, which will be useful for understanding their function in signal transduction.