Abstract
Relaxin family peptides perform a variety of biological functions by activating four G protein-coupled receptors, namely RXFP1–4. Among these receptors, RXFP3 lacks a specific natural or synthetic agonist at present. A previously designed chimeric R3/I5 peptide, consisting of the B-chain of relaxin-3 and the A-chain of INSL5, displays equal activity towards the homologous RXFP3 and RXFP4. To increase its selectivity towards RXFP3, in the present study we conducted extensive mutagenesis around the B-chain C-terminal region of R3/I5. Decreasing or increasing the peptide length around the B23–B25 position dramatically lowered the activation potency of R3/I5 towards both RXFP3 and RXFP4. Substitution of B23Gly with Ala or Ser converted R3/I5 from an efficient agonist to a strong antagonist for RXFP3, but the mutants retained considerable activation potency towards RXFP4. Substitution of B24Gly increased the selectivity of R3/I5 towards RXFP3 over the homologous RXFP4. The best mutant, [G(B24)S]R3/I5, displayed 20-fold higher activation potency towards RXFP3 than towards RXFP4, meanwhile retained full activation potency at RXFP3. Thus, [G(B24)S]R3/I5 is the best RXFP3-selective agonist known to date. It is a valuable tool for investigating the physiological functions of RXFP3, and also a suitable template for developing RXFP3-specific agonists in future.
Highlights
Relaxin family is a group of peptide hormones, including relaxin, relaxin-3, and insulin-like peptide 3–6 (INSL3-6)[1,2,3,4,5]
The resultant mature mutants were further purified by high performance liquid chromatography (HPLC) and their identities were confirmed by mass spectrometry
We developed a selective and fully active agonist for RXFP3, [G(B24)S]R3/I5, by extensive mutagenesis of the B-chain C-terminal region of the chimeric R3/I5 peptide
Summary
Relaxin family is a group of peptide hormones, including relaxin (primates have two relaxin genes), relaxin-3, and insulin-like peptide 3–6 (INSL3-6)[1,2,3,4,5]. To generate an agonist with higher selectivity for RXFP3, in the present study we conducted extensive mutagenesis around the B-chain C-terminal region of the chimeric R3/I5 peptide. We substituted the highly conserved B23Gly, B24Gly, and B25Ser residues with some other amino acids These substitutions likely affect the flexibility of the B-chain C-terminus and might modulate receptor selectivity of R3/I5. Using these approaches, we obtained a selective and fully active agonist for RXFP3, [G(B24)S]R3/I5, that displayed 20-fold higher activation potency towards RXFP3 than towards RXFP4, and retained full activity at RXFP3 compared with wild-type R3/I5. To our knowledge, [G(B24)S]R3/I5 is the best RXFP3-selective agonist known to date
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
