Motilin receptor

Motilin receptor is a G protein-coupled receptor (previously GPCR38)^[3][4][5] that binds motilin.^[6][7] It was first cloned in 1999 by Merck Laboratories.^[8] and scientists have since been searching for compounds to modify its behavior.^[9]

MLNR
Identifiers
Aliases	MLNR, GPR38, MTLR1, motilin receptor
External IDs	OMIM: 602885; HomoloGene: 74398; GeneCards: MLNR; OMA:MLNR - orthologs
Gene location (Human) Chr. Chromosome 13 (human)[1] Band 13q14.2 Start 49,220,338 bp[1] End 49,222,377 bp[1]
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in testicle gonad bone marrow fundus body of stomach islet of Langerhans blood stromal cell of endometrium right lobe of thyroid gland kidney n/a More reference expression data BioGPS More reference expression data
Gene ontology Molecular function growth hormone-releasing hormone receptor activity signal transducer activity G protein-coupled receptor activity G protein-coupled peptide receptor activity hormone binding Cellular component integral component of membrane plasma membrane membrane Biological process G protein-coupled receptor signaling pathway signal transduction Sources:Amigo / QuickGO
Orthologs Species Human Mouse Entrez 2862 n/a Ensembl ENSG00000102539 n/a UniProt O43193 n/a RefSeq (mRNA) NM_001507 n/a RefSeq (protein) NP_001498 n/a Location (UCSC) Chr 13: 49.22 – 49.22 Mb n/a PubMed search [2] n/a
Wikidata
View/Edit Human

The primary structure of the motilin receptor consists of 412 amino acids,^[8] while its tertiary structure resembles a golf club.^[10] The protein C-terminal protein protects from enzymatic degradation, while the N-terminal is essential for binding.^[10]

Function

The primary function of the motilin receptor is to contract gastric smooth muscle during phase III of the migrating motor complex (MMC).^[8] In this final phase of the MMC, N-type motilin receptors in the distal antral pump of the stomach are activated.^[11] This causes contraction of the gastric smooth muscle, sieving food into the small intestine, and priming the stomach for the next meal.^[12]

Motilin

Motilin is an intestinal peptide that stimulates the contraction of gastric smooth muscle via the motilin receptor.^[8] It is produced by enteroendocrine cells in the proximal small intestine^[3][13] and secreted cyclically.^[14] Motilin mimetics could be used to increase gastric motility in patients with gastroparesis e.g., constipation-predominant irritable bowel syndrome.^[15] However, none of the candidate drugs that have been tested so far have made it to market.^[4][16]