T1R2

T1R2 is a subunit of the taste receptor type 1 (T1R) family. In humans it is encoded by the TAS1R2 gene and is mainly expressed in taste receptor cells of the tongue. T1R2 forms a functional sweet taste receptor in partnership with the related subunit T1R3, creating the heterodimer T1R2/T1R3 that detects a broad range of sweet compounds. Homodimers of T1R2 or T1R3 alone have little activity, so the heterodimer is essential for sweet signal transduction.

Functionally, T1R2/T1R3 is a G protein-coupled receptor that signals through the gustducin pathway. Upon ligand binding, it activates phospholipase Cβ2, leading to the production of inositol trisphosphate and diacylglycerol, an increase in intracellular calcium, and the opening of the TRPM5 channel. These events depolarize taste receptor cells and trigger neurotransmitter release to gustatory neurons, enabling the perception of sweetness.

Expression and roles extend beyond the tongue. While T1R2 is primarily associated with taste, the receptor has also been detected in some gut enteroendocrine cells, where it may participate in nutrient sensing and the regulation of hormone release. This extraoral expression suggests a broader role in energy intake and metabolic signaling.

Ligands recognized by T1R2/T1R3 include natural sugars such as glucose, sucrose, and fructose, as well as many artificial sweeteners. Specific ligand profiles can vary among species, and genetic variation in TAS1R2 can influence individual sensitivity to sweet tastes.

See also: TAS1R2, taste receptor type 1, sweet taste receptor.