RXFP1 Membrane Protein Introduction

Introduction of RXFP1

RXFP1, also known as LGR7 or RXFPR1, is a member of the subfamily of GPCRs which is characterized with a large ectodomain containing a single LDL class A (LDLa) module, an LDLa linker and 10 leucine-rich repeats (LRRs). As a cognate receptor for relaxin, RXFP1 was initially discovered in 2002. Typical of leucine-rich repeat-containing GPCRs, the 7TM domain of RXFP1 has three extracellular loops and three intracellular loops that play a role in the induction of cellular signaling responses upon peptide binding.

Basic Information of RXFP1
Protein Name Relaxin receptor 1
Gene Name RXFP1
Aliases Leucine-rich repeat-containing G-protein coupled receptor 7, Relaxin family peptide receptor 1
Organism Homo sapiens (Human)
UniProt ID Q9HBX9
Transmembrane Times 7
Length (aa) 757

Function of RXFP1 Membrane Protein

Relaxin is a small heterodimeric peptide hormone of the insulin/relaxin superfamily which is mainly produced in the ovarian corpora lutea and placenta in females and in prostate in males. It was initially identified as a hormone affecting pubic symphysis relaxation during parturition in rodents. Studies have shown that Relaxin has potent antifibrotic, vasodilatory and angiogenic effects and regulates the normal function of various physiological systems. RXFP1, also known as leucine-rich repeat G-protein coupled receptor (LGR7), is a cognate receptor of RLN and expressed in placenta. It has been reported that RLN and RXFP1 are expressed by the endothelium and vascular smooth muscle of the systemic vasculature in rodents and RXFP1 in umbilical endothelium and vascular smooth muscle in humans. What’s more, RXFP1 plays a critical role in sperm motility, pregnancy and parturition as a receptor for the protein hormone relaxin. Decreased expression of this gene may play a role in endometriosis.

Schematic representation of the RXFP1 and RXFP2 receptors compared to the RXFP211, RXFP122, RXFP212, and RXFP121 chimeric receptors. Fig.1 Schematic representation of the RXFP1 and RXFP2 receptors compared to the RXFP211, RXFP122, RXFP212, and RXFP121 chimeric receptors. (Bruell, 2013)

Application of RXFP1 Membrane Protein in Literature

  1. Agoulnik A.I., et al. Synthetic non-peptide low molecular weight agonists of the relaxin receptor 1. British journal of pharmacology. 2017, 174(10):977-89. PubMed ID: 27771940

    This article reports that low MW agonists does not activate rodent RXFP1 receptors and the production of a RXFP1 humanized mouse model is needed for preclinical studies.

  2. Dehghan F., et al. Estrogen receptor (ER)-α, β, and progesterone receptor (PR) mediates changes in relaxin receptor (RXFP1 and RXFP2) expression and passive range of motion of rats’ knee. Environmental toxicology and pharmacology. 2015, 40(3):785-91. PubMed ID: 26447688

    This article examines changes in knee range of motion in presence of estrogen and progesterone and investigates the interaction of their antagonists to relaxin receptors. It suggests that progesterone and high doses of estrogen treatment results in the highest range of knee laxity correlated to expression of both relaxin receptor (RXFP1 and RXFP2) isoforms in knee tissues. And female subjects are more vulnerable toward non-traumatic knee injury due to estrogen and progesterone fluctuation as compared to male subjects.

  3. Kaftanovskaya E.M., Conditional deletion of the relaxin receptor gene in cells of smooth muscle lineage affects lower reproductive tract in pregnant mice. Biology of reproduction. 2015, 92(4):91-1. PubMed ID: 25715795

    This article indicates that relaxin/RXFP1 signaling in smooth muscle cells is important for normal collagen turnover and relaxation of the pubic symphysis during pregnancy.

  4. Kong R.C., et al. The relaxin receptor (RXFP1) utilizes hydrophobic moieties on a signaling surface of its N-terminal low density lipoprotein class A module to mediate receptor activation. Journal of Biological Chemistry. 2013, 288(39):28138-51. PubMed ID: 23926099

    This article confirms that an RXFP1 receptor lacking the LDLa module binds ligand normally but cannot signal through any characterized G protein-coupled receptor signaling pathway.

  5. Xiao J., et al. Discovery, optimization, and biological activity of the first potent and selective small-molecule agonist series of human relaxin receptor 1 (RXFP1). 2013. PubMed ID: 23905199

    This article reveals that ML290 could be used as a very useful tool for the study of RXFP1 activation in pre-clinical disease models of heart failure and other diseases, and might provide a lead for the development of a small-molecule drug as an alternative to the current expensive recombinant human relaxin therapy.

RXFP1 Preparation Options

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  1. Bruell, et al. (2013). Chimeric RXFP1 and RXFP2 receptors highlight the similar mechanism of activation utilizing their N-terminal low-density lipoprotein class A modules. Frontiers in Endocrinology. 4: 171.

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