Sweet taste receptor T1R3 subunit (T1R3)

The Sweet taste receptor T1R3 subunit is one component of the heterodimeric sweet taste receptor complex found primarily on the tongue. This complex consists of two class C G protein-coupled receptors—T1R2 and T1R3—that together form the functional sweet taste sensor responsible for detecting a wide variety of chemically diverse compounds including natural sugars, artificial sweeteners such as aspartame and neotame, some d-amino acids, and certain proteins[1][2][4]. The T1R3 subunit can also pair with another family member (T1R1) to form an umami (savory) taste receptor sensitive to amino acids like glutamate[2][3]. Structurally, both subunits have large extracellular Venus flytrap domains for ligand binding connected by cysteine-rich regions to seven-transmembrane domains typical of GPCRs[5]. Upon ligand binding at specific sites on either or both subunits—depending on the compound—the heterodimer undergoes conformational changes that activate downstream signaling through gustducin-containing G proteins. This leads to phospholipase C activation and subsequent calcium release from intracellular stores—a process essential for transmitting "sweet" signals from sensory cells to nerves involved in flavor perception[2][4]. While primarily studied in oral tissues for their role in gustation, these receptors are also expressed extraorally where they may influence glucose absorption or hormone secretion. The T1R3 itself is not active alone but is essential for forming functional complexes with either T1R2 or T1R1.

Other names

Taste receptor type 1 member 3TAS1R3T1R3 subunitSweet/umami taste receptor subunit T1R3

Ligand binding induces conformational change in the heterodimeric T1R2/T1R3 complex, activating intracellular G protein signaling pathways leading to increased intracellular calcium and neuronal activation associated with sweet taste perception[2][3].