TAS2R38

TAS2R38 is a gene that encodes a member of the TAS2R (taste receptor, type 2) family of proteins in humans. These receptors are part of the G protein-coupled receptor superfamily and are involved in the perception of bitter taste. The TAS2R38 gene is located on chromosome 7 (7q34) in humans and is responsible for variations in the ability to taste certain bitter compounds, particularly phenylthiocarbamide (PTC) and related chemicals.

Function

The TAS2R38 protein is expressed in the taste receptor cells of the tongue and is responsible for detecting the presence of certain bitter compounds. When these compounds bind to the TAS2R38 receptor, a signal is sent to the brain, resulting in the perception of bitterness. This mechanism is part of the body's ability to detect potentially toxic substances, many of which are bitter, and avoid consuming them.

Genetic Variability and Taste Perception

The TAS2R38 gene exhibits significant polymorphism, with several common alleles leading to variations in bitter taste perception among individuals. The most well-studied variants are the PAV (proline-alanine-valine) and AVI (alanine-valine-isoleucine) haplotypes. Individuals homozygous for the PAV allele (PAV/PAV) are generally sensitive to the taste of PTC and related compounds, while those with the AVI/AVI genotype are typically insensitive. Heterozygotes (PAV/AVI) often have intermediate sensitivity.

This genetic variability has been the subject of numerous studies, as it not only affects dietary preferences and nutrition but also has implications for health and medicine, including the efficacy and side effects of certain medications that may taste bitter.

Evolutionary Significance

The variation in TAS2R38 and its impact on bitter taste perception is thought to have evolutionary significance. The ability to detect bitter tastes likely conferred an advantage in environments where toxic plants were common, as it would help to avoid ingestion of harmful substances. The diversity in TAS2R38 suggests that different populations have adapted to their specific diets and environments over time.

Clinical Significance

Research has explored the relationship between TAS2R38 genotypes and various health outcomes, including dietary preferences, nutritional status, and susceptibility to certain diseases. For example, individuals who are more sensitive to bitter tastes may avoid bitter vegetables, potentially impacting their intake of beneficial nutrients. Additionally, variations in TAS2R38 have been studied in the context of sinus infections, as the receptor is also expressed in the respiratory system, where it may play a role in immune response.

See Also

• Taste receptor
• G protein-coupled receptor
• Phenylthiocarbamide
• Genetic polymorphism