Taste receptor type 1 member 1 and Taste receptor type 1 member 3 complex (T1R1/T1R3)

The umami taste receptor is a heterodimeric G protein-coupled receptor (GPCR) formed by the association of Taste receptor type 1 member 1 (T1R1) and Taste receptor type 1 member 3 (T1R3) (Nelson et al., 2002). It serves as the primary sensor for L-amino acids, particularly L-glutamate and L-aspartate, which provide the savory or umami flavor profile essential for identifying protein-rich food sources (Li et al., 2002). Beyond its well-characterized role in the oral cavity, the T1R1/T1R3 complex is expressed in various extra-oral tissues, including the stomach, small intestine, and pancreas, where it functions as a nutrient sensor to regulate the secretion of metabolic hormones such as glucagon-like peptide-1 (GLP-1) and insulin (Mace et al., 2009). Dysregulation or genetic variations in these receptors have been linked to metabolic conditions such as obesity and type 2 diabetes, as they influence dietary preferences and glucose homeostasis (Kokrashvili et al., 2009). Pharmacologically, the receptor is a target for flavor enhancers like monosodium glutamate (MSG) and ribonucleotides, and it is being explored for therapeutic potential in modulating appetite and metabolic health. Understanding the signaling and distribution of T1R1/T1R3 provides a pathway for developing novel treatments for metabolic syndrome and nutritional disorders.

Other names

TAS1R1/TAS1R3Umami taste receptorL-amino acid receptorG-protein coupled receptor 70T1R1+3

The T1R1/T1R3 complex functions as a Venus flytrap-like receptor where L-amino acids bind to the extracellular Venus flytrap domain of the T1R1 subunit, inducing a conformational change in the heterodimer. This activation triggers a G protein-mediated signaling cascade (involving G-alpha-gustducin or G-alpha-i/o) that activates phospholipase C beta-2 (PLC-beta-2), leading to the production of IP3 and the release of intracellular calcium, which subsequently opens the TRPM5 ion channel to cause cellular depolarization and neurotransmitter release (Nelson et al., 2002; Li et al., 2002).