Olfactory receptors interact with odorant molecules in the nose, to initiate a neuronal response that triggers the perception of a smell. The olfactory receptor proteins are members of a large family of G-protein-coupled receptors (GPCR) arising from single coding-exon genes. Olfactory receptors share a 7-transmembrane domain structure with many neurotransmitter and hormone receptors and are responsible for the recognition and G protein-mediated transduction of odorant signals. The olfactory receptor gene family is the largest in the genome. OR51E1 has been shown to be expressed in enteroendocrine cells in the intestine, modulated by intestinal microbiota, as well as mediating GLP-1 secretion. References: https://doi.org/10.1371/journal.pone.0129501; Journal of the Endocrine Society, Volume 2, Issue 11, November 2018, Pages 1251–1258