Top ▲

Relaxin family peptide receptors C

Unless otherwise stated all data on this page refer to the human proteins. Gene information is provided for human (Hs), mouse (Mm) and rat (Rn).


« Hide More detailed introduction

Relaxin family peptide receptors (RXFP, nomenclature as agreed by the NC-IUPHAR Subcommittee on Relaxin family peptide receptors [4,16]) may be divided into two pairs, RXFP1/2 and RXFP3/4. Endogenous agonists at these receptors are heterodimeric peptide hormones structurally related to insulin: relaxin-1 (RLN1, P04808), relaxin (RLN2, P04090), relaxin-3 (RLN3, Q8WXF3) (also known as INSL7), insulin-like peptide 3 (INSL3 (INSL3, P51460)) and INSL5 (INSL5, Q9Y5Q6). Species homologues of relaxin have distinct pharmacology and relaxin (RLN2, P04090) interacts with RXFP1, RXFP2 and RXFP3, whereas mouse and rat relaxin selectively bind to and activate RXFP1 [45]. Relaxin-3 (RLN3, Q8WXF3) is the ligand for RXFP3 but it also binds to RXFP1 and RXFP4 and has differential affinity for RXFP2 between species [44]. INSL5 (INSL5, Q9Y5Q6) is the ligand for RXFP4 but is a weak antagonist of RXFP3. Relaxin (RLN2, P04090) and INSL3 (INSL3, P51460) have multiple complex binding interactions with RXFP1 [48] and RXFP2 [21] which direct the N-terminal LDLa modules of the receptors together with a linker domain to act as a tethered ligand to direct receptor signaling [46]. INSL5 (INSL5, Q9Y5Q6) and relaxin-3 (RLN3, Q8WXF3) interact with their receptors using distinct residues in their B-chains for binding, and activation, respectively [28,60].


RXFP1 C Show summary » More detailed page

RXFP2 C Show summary » More detailed page

RXFP3 C Show summary » More detailed page

RXFP4 C Show summary » More detailed page


Show »

Further reading

Show »


Show »

NC-IUPHAR subcommittee and family contributors

Show »

How to cite this family page

Database page citation (select format):

Concise Guide to PHARMACOLOGY citation:

Alexander SPH, Christopoulos A, Davenport AP, Kelly E, Mathie A, Peters JA, Veale EL, Armstrong JF, Faccenda E, Harding SD, Pawson AJ, Sharman JL, Southan C, Davies JA; CGTP Collaborators. (2019) The Concise Guide to PHARMACOLOGY 2019/20: G protein-coupled receptors. Br J Pharmacol. 176 Issue S1: S21-S141.