Bitter taste perception is mediated by members of the highly divergent TAS2R receptor family. TAS2Rs are expressed primarily in taste cells and have evolved to detect an extraordinary diversity of bitter compounds that are naturally found in foods and toxins, translating that detection into gustatory perception via G protein coupled signaling. While the molecular specificity of human TAS2Rs have been delineated in detail, much less in known about the specificities of TAS2Rs from other species. We have initiated work to understand bitter taste perception and TAS2R function in cats. Several studies have described the phylogenetic relationship of specific feline bitter sequences as compared to other carnivores; however, no studies have examined feline taste perception through functional expression of feline taste receptors. As felines are obligate carnivores, in which the sweet receptor TAS1R2 has become a pseudogene, it may be misleading to make the assumption that feline perception of bitter is similar to other mammals. We have cloned the sequences for feline TAS2R38 and TAS2R43 and deorphanized these receptors using a cellular functional assay. We demonstrate that the response profiles of the feline bitter receptors TAS2R38 and TAS2R43 are distinct from those of the homologous human receptors. Human and feline TAS2R38 both respond to the presence of phenylthiocarbamide (PTC), the prototypical TAS2R38 ligand, but show drastically different sensitivity to other known TAS2R38 ligands. Similarly, both human and feline TAS2R43 are responsive to aloin but differ in sensitivity and specificity to other known TAS2R ligands. Based on this knowledge we can begin to understand what chemicals felines can detect through bitter receptors and provide either a better tasting food through elimination of ingredients or through addition of bitter blockers. Future work will focus on deorphanizing of additional receptors as well as testing identified compounds perceptually in cats.

Feline bitter receptors TAS2R38 and TAS2R43 have response profiles distinct from the human homologues

249th National Meeting (2015)

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