The sequence of the hemoregulatory peptide is present in G proteins

Abstract
The hemoregulatory peptide PyroGlu‐Glu‐Asp‐Cys‐Lys (HP5b), which inhibits myelopoietic colony formation in vitro, is shown to be a sequence motif which is also part of the effector domain of G proteins. Out of 8 synthetic peptides with sequence variations of HP5b, those with the closest similarity to the G sequence are biologically active. The inhibitory effect appears to be dependent on the blocked N‐tenninus. It is postulated that these peptides may interfere with signal transduction mediated by Gα proteins.