Identification and characterization of human taste receptor genes belonging to the TAS2R family

Abstract

The sense of taste is a chemosensory system responsible for basic food appraisal. Humans distinguish between five primary tastes: bitter, sweet, sour, salty and umami. The molecular events in the perception of bitter taste are believed to start with the binding of specific water-soluble molecules to G-protein-coupled receptors encoded by the TAS2R/T2R family of taste receptor genes. TAS2R receptors are expressed at the surface of taste receptor cells and are coupled to G proteins and second messenger pathways. We have identified, cloned and characterized 11 new bitter taste receptor genes and four new pseudogenes that belong to the human TAS2R family. Their encoded proteins have between 298 and 333 amino acids and share between 23 and 86% identity with other human TAS2R proteins. Screening of a mono-chromosomal somatic cell hybrid panel to assign the identified bitter taste receptor genes to human chromosomes demonstrated that they are located in chromosomes 7 and 12. Including the 15 sequences identified, the human TAS2R family is composed of 28 full-length genes and 16 pseudogenes. Phylogenetic analyses suggest a classification of the TAS2R genes in five groups that may reflect a specialization in the detection of specific types of bitter chemicals.

Molecular cloning and evolutionary analysis of captive forest musk deer bitter taste receptor gene T2R16

“…The nearly complete human and mouse T2R gene repertoires have been elucidated (Conte et al, 2002(Conte et al, , 2003Shi et al, 2003). Some valuable studies of Hu and Shi (2013) and Dong et al (2009) demonstrated the smallest bitter taste receptor (T2Rs) gene repertoire in carnivores and the dynamic evolution of bitter taste receptor genes in vertebrates, respectively.…”

“…T2Rs are the largest family of taste receptors, which bind to tastants. Like olfactory and other chemosensory receptor genes, T2R genes also form a multi-gene family and display high sequence similarity (Conte et al, 2002;Shi et al, 2003). Coding regions of T2Rs contain an average of 300 codons, and they are not interrupted by introns, rendering them easy to be detected in whole-genome sequences.…”

“…This family is subject to high rates of genetic variation (Chandrashekar et al, 2006;Bachmanov and Beauchamp, 2007) which is likely to reflect dietary changes during the animal's evolution (Behrens and Meyerhof, 2009). In previous studies, T2R gene repertoires have been uncovered in some mammals, chickens, frogs, and some teleost fishes (Matsunami et al, 2000;Conte et al, 2002Conte et al, , 2003Parry et al, 2004;Wang et al, 2004;Go et al, 2005;Shi et al, 2003;Shi and Zhang, 2006). The nearly complete human and mouse T2R gene repertoires have been elucidated (Conte et al, 2002(Conte et al, , 2003Shi et al, 2003).…”

“…In previous studies, T2R gene repertoires have been uncovered in some mammals, chickens, frogs, and some teleost fishes (Matsunami et al, 2000;Conte et al, 2002Conte et al, , 2003Parry et al, 2004;Wang et al, 2004;Go et al, 2005;Shi et al, 2003;Shi and Zhang, 2006). The nearly complete human and mouse T2R gene repertoires have been elucidated (Conte et al, 2002(Conte et al, , 2003Shi et al, 2003). Current genome annotation records suggest that there are more than 30 putative functional T2Rs in the mouse genome, while they are fewer in humans, and most have close homologs in mouse (Matsunami et al, 2000;Wu et al, 2005).…”

Extraordinary Diversity of Chemosensory Receptor Gene Repertoires Among Vertebrates

“…In 2000, the T2R gene family (also known as TRBs or Tas2Rs) was identified and two mouse T2R genes were shown to be bitter taste receptors Chandrashekar et al 2000 ;Matsunami et al 2000) . To date, the complete T2R gene repertoires have been described in mammals, birds, amphibians, and some fishes (Conte et al 2002(Conte et al , 2003Go 2006 ;Shi and Zhang 2006) . In addition, a small number of T2R genes have also been described in several nonhuman primates (Parry et al 2004 ;Wang et al 2004 ;Fischer et al 2005 ;Go et al 2005) .…”