RXFP4 Membrane Protein Introduction

Introduction of RXFP4

Relaxin-3 Receptor 2 (RXFP4), also known as GPCR142 or GPR100, is encoded by the RXFP4 gene. It belongs to the G-protein-coupled receptor (GPCR) family, and is a high-affinity receptor for INSL5. It opened a new area for the research of the insulin-like peptides. It also acts as a receptor for RLN3/relaxin-3, as well as bradykinin and kallidin. RXFP4 and RXFP3 share about 40% amino acid identity and overall share 50% homology.

Basic Information of RXFP4
Protein Name	Relaxin-3 Receptor 2
Gene Name	RXFP4
Aliases	RLN3R2, GPCR142, GPCR100
Organism	Homo sapiens (Human)
UniProt ID	Q8TDU9
Transmembrane Times	7
Length (aa)	374
Sequence	MPTLNTSASPPTFFWANASGGSVLSADDAPMPVKFLALRLMVALAYGLVGAIGLLGNLAVLWVLSNCARRA PGPPSDTFVFNLALADLGLALTLPFWAAESALDFHWPFGGALCKMVLTATVLNVYASIFLITALSVARYWV VAMAAGPGTHLSLFWARIATLAVWAAAALVTVPTAVFGVEGEVCGVRLCLLRFPSRYWLGAYQLQRVVLAF MVPLGVITTSYLLLLAFLQRRQRRRQDSRVVARSVRILVASFFLCWFPNHVVTLWGVLVKFDLVPWNSTFY TIQTYVFPVTTCLAHSNSCLNPVLYCLLRREPRQALAGTFRDLRLRLWPQGGGWVQQVALKQVGRRWVASNP RESRPSTLLT NLDRGTPG

Function of RXFP4 Membrane Protein

G proteins, resulting in the activation of adenylyl cyclase and elevating intracellular cAMP, mediate the activity of RXFP4. RXFP4 was activated by nanomolar concentrations of relaxin-3 but was completely unresponsive to all other known insulin-like peptides. Reverse transcriptase-PCR shows the expression of RXFP4 mRNA in a variety of human tissues and found that it is expressed in brain, kidney, testis, thymus, placenta, prostate, salivary gland, thyroid, and colon. Some scholars believe it may be involved in the regulation of glucose and lipid metabolism.

Fig.1 Relaxin family peptide receptors RXFP3 and RXFP4.

Application of RXFP4 Membrane Protein in Literature

Liu C., et al. Identification of relaxin-3/INSL7 as a ligand for GPCR142. Biol Chem. 2003, 218(50): 50765-70. PubMed ID: 14522967

Author’s team identified the insulin-like peptide relaxin-3 (aka INSL7) as the endogenous ligand for an orphan G-protein-coupled receptor. RXFP4 could also respond to relaxin-3 or related insulin-like molecules.
Liu C., et al. INSL5 is a high affinity specific agonist for GPCR142 (GPR100). Biol Chem. 2005, 280(1): 292-300. PubMed ID:15535639

This article suggests that INSL5 is an endogenous ligand for RXFP4.
Boels K., et al. Identification and characterisation of GPR100 as a novel human G-protein-coupled bradykinin receptor. Pharmacol. 2003, 140(5): 932-8. PubMed ID: 14530218

This article reveals that GPR100 was expressed predominantly in tissues like pancreas, heart, skeletal muscle, salivary gland, bladder, kidney, liver, placenta, stomach, jejunum, thyroid gland, ovary, and bone marrow, but smaller amounts were also detected in the brain and in cell lines derived from tumours of various origins.
Zhu J., et al. Identification of the domains in RXFP4 (GPCR142) responsible for the high affinity binding and agonistic activity of INSL5 at RXFP4 compared to RXFP3 (GPCR135). Pharmacol. 2008, 590(1-3): 43-52. PubMed ID: 18582868

This article suggests that the N-terminus and EL2 domains of RXFP3 and RXFP4 are involved in ligand binding while TM2, 3, and 5 are critical for receptor activation.
Wang X.Y., et al, Identification of important residues of insulin-like peptide 5 and its receptor RXFP4 for ligand-receptor interactions. FEBS. 2014, 558: 127-32. PubMed ID: 25043977

This article proposes probable electrostatic interactions between INSL5 and RXFP4: the B-chain central B13Arg of INSL5 interacts with both Asp104 and Glu182 of RXFP4, meanwhile the B-chain C-terminal B23Arg of INSL5 interacts with both Glu100 and Asp104 of RXFP4.

RXFP4 Preparation Options

To obtain the soluble and functional target protein, the versatile Magic™ membrane protein production platform in Creative Biolabs enables many flexible options, from which you can always find a better match for your particular project. Aided by our versatile Magic™ anti-membrane protein antibody discovery platform, we also provide customized anti-RXFP4 antibody development services.

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