Our identification of the EBC5-16 homodimer interface provides the foundation for further mechanistic studies and allows us to better understand how these small transmembrane proteins function and interact with their target. In comparison to TC2-3, EBC5-16 supports growth factor independence at lower expression levels and is more effective at inducing erythroid differentiation. The enhanced dimerization of EBC5-16 presumably increases its ability to activate the hEPOR or causes a quantitative or Felodipine qualitative change in signaling output. However, the levels of tyrosine phosphorylation of the hEPOR, JAK2, and STAT5 were similar in cells expressing EBC5-16 and TC2-3. We hypothesize that TC2-3 and EBC5-16 induce an asyet-unidentified difference in EPOR signaling, for example, by affecting which specific tyrosines are phosphorylated. Similarly, different orientations of the EPOR intracellular domains can result in qualitatively different signaling outcomes. It is also possible that the signaling output of the EPOR in response to EBC5-16 differs in some regards from the output of EPO-stimulated receptor. In fact, EBC5-16 stimulates some aspects of erythroid differentiation, such as GpA expression, better than others,Ranolazine dihydrochloride suggesting that EPOR-mediated erythoid differentiation is not an all-or-nothing process. Further analysis of EPOR signaling in response to various activators may reveal new aspects of EPOR action. As well as illuminating aspects of transmembrane protein interactions and cell physiology, our results may have practical implications. Transmembrane domains derived from native proteins have been added to cells as peptides or expressed as short proteins, resulting in their incorporation into cell membranes and biological activity. In fact, hydrophobic peptides derived from a naturally-occurring transmembrane domain can localize to appropriate tissues after systemic injection into animals. Our results indicate that artificial transmembrane proteins may also be the source of biologically active hydrophobic peptides, which may have important research and even clinical uses. Similarly, genes encoding small, cell-autonomous, transmembrane proteins may find use in ex vivo gene therapy.