G protein-coupled receptor 42 (GPR42)

G protein-coupled receptor 42 (GPR42) is a putative G protein-coupled receptor and probable segmental duplicate of the Free fatty acid receptor 3 (FFAR3/GPR41) gene, located on human chromosome 19q13.33[2][4]. Historically classified as a pseudogene in humans, recent evidence shows that GPR42 is transcribed and exhibits copy number variation and extensive polymorphism in the human population[4]. Most GPR42 alleles differ from FFAR3 by only a single amino acid, and some forms are predicted to be functional, although their precise endogenous ligands, expression pattern, pharmacology, and physiological role remain unclear and are not established in curated databases as of June 2025[2][4]. There is no direct evidence of druggability or clinical targeting for GPR42, and its status as a functional receptor versus a pseudogene varies by haplotype and remains unresolved. GPR42's closest characterized homologs, such as FFAR3 (GPR41), are activated by short-chain fatty acids and implicated in energy metabolism, intestinal immunity, and some metabolic diseases, but these functions should not automatically be ascribed to GPR42 without further evidence[3][4]. GPR42 may encode a functional G protein-coupled receptor in some human haplotypes, but is often a pseudogene, and currently lacks defined endogenous ligands, clinical targeting, or established physiological function. Its classification as a therapeutic target is not supported by current literature or databases[2][3][4].

Other names

FFAR1LFFAR3LGPR41LGPR42PG-protein coupled receptor 42 pseudogeneFree fatty acid receptor 3-like