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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).


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Relaxin family peptide receptors (RXFP, nomenclature as agreed by the NC-IUPHAR Subcommittee on Relaxin family peptide receptors [2,12]) may be divided into two pairs, RXFP1/2 and RXFP3/4. Endogenous agonists at these receptors are a number of 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 – relaxin (RLN2, P04090) interacts with RXFP1, RXFP2 and RXFP3, whereas mouse and rat relaxin selectively bind to and activate RXFP1 [34] and porcine relaxin may have a higher efficacy than human relaxin (RLN2, P04090) [13]. Relaxin-3 (RLN3, Q8WXF3) has differential affinity for RXFP2 between species; mouse and rat RXFP2 have a higher affinity for relaxin-3 (RLN3, Q8WXF3) [33]. At least two binding sites have been identified on RXFP1 and RXFP2: a high-affinity site in the leucine-rich repeat region of the ectodomain and a somewhat lower-affinity site located in the surface loops of the transmembrane domain [13,43]. The unique N-terminal LDLa module of RXFP1 and RXFP2 is essential for receptor signalling [35].


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


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Further reading

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NC-IUPHAR subcommittee and family contributors

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How to cite this family page

Database page citation:

Roger Summers, Ross Bathgate, Thomas Dschietzig, Andrew L. Gundlach, Michelle Halls. Relaxin family peptide receptors. Accessed on 20/03/2019. IUPHAR/BPS Guide to PHARMACOLOGY,

Concise Guide to PHARMACOLOGY citation:

Alexander SPH, Christopoulos A, Davenport AP, Kelly E, Marrion NV, Peters JA, Faccenda E, Harding SD, Pawson AJ, Sharman JL, Southan C, Davies JA; CGTP Collaborators. (2017) The Concise Guide to PHARMACOLOGY 2017/18: G protein-coupled receptors. Br J Pharmacol. 174 Suppl 1: S17-S129.