Pyroglutamylated RFamide Peptide

Novel RFamide Peptide was discoverd utilizing the Gene Database!

The group of Takeda Chemical Industries Ltd. has long been involved in discovering orphan receptor ligands and has now identified a novel peptide in human utilizing the recently established gene database. Actually, they searched the database to detect peptides with the carboxyl-terminal Arg-Phe-NH2 (RFamide) moiety in the mature peptide. As a result, the peptide termed pyroglutamylated RFamide peptide (QRFP) was identified by analyzing the expressed peptide in Chinese hamster ovary cells as a 43 amino acid residue peptide [ J. Biol. Chem., 278, 46387 (2003) ]. The peptide corresponding to the carboxyl-terminal 26 amino acid residues of QRFP was also predicted by another group using a similar approach and then termed P518 [J. Biol. Chem., 278, 27652 (2003)]. Both of these peptides were found to interact with an orphan receptor (AQ27/SP9155/GPR103; all of these denote the same orphan receptor of interest). Human 26RFa was proposed by another group based on the primary structure of their determined frog peptide in which 26RFa is identical to P518 [ Proc. Natl. Acad. Sci. U.S.A., 100, 15247 (2003) ].

The biological activities of QRFP and 26RFa reported so far are: i) upon intravenous administration in rats at doses between 40 and 400 nmol/kg, QRFP induced aldosterone secretion in a dose-dependent manner, and ii) intracerebroventricular administration of 26RFa in mice (after partial food deprivation for 18 h) stimulated food intake at doses of 100 and 1000 ng/mouse.

This newly identified peptide, QRFP, might have variable activities other than those identified so far, thus, it should serve as an essential member of the RFamide family peptides in humans.