Higgins Kathleen W, Itoigawa Akihiro, Toda Yasuka, Bellott Daniel Winston, Anderson Rachel, Márquez Roberto, Weng Jing-Ke
Whitehead Institute of Biomedical Research, Cambridge, Massachusetts, United States of America.
Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America.
PLoS Genet. 2025 Jan 31;21(1):e1011533. doi: 10.1371/journal.pgen.1011533. eCollection 2025 Jan.
TAS2Rs are a family of G protein-coupled receptors that function as bitter taste receptors in vertebrates. Mammalian TAS2Rs have historically garnered the most attention, leading to our understanding of their roles in taste perception relevant to human physiology and behaviors. However, the evolution and functional implications of TAS2Rs in other vertebrate lineages remain less explored. Here, we identify 9,291 TAS2Rs from 661 vertebrate genomes. Large-scale phylogenomic analyses reveal that frogs and salamanders contain unusually high TAS2R gene content, in stark contrast to other vertebrate lineages. In most species, TAS2R genes are found in clusters; compared to other vertebrates, amphibians have additional clusters and more genes per cluster. We find that vertebrate TAS2Rs have few one-to-one orthologs between closely related species, although total TAS2R count is stable in most lineages. Interestingly, TAS2R count is proportional to the receptors expressed solely in extra-oral tissues. In vitro receptor activity assays uncover that many amphibian TAS2Rs function as tissue-specific chemosensors to detect ecologically important xenobiotics.
味觉受体2型（TAS2Rs）是一类G蛋白偶联受体，在脊椎动物中作为苦味受体发挥作用。历史上，哺乳动物的TAS2Rs受到了最多关注，这使我们了解了它们在与人类生理和行为相关的味觉感知中的作用。然而，TAS2Rs在其他脊椎动物谱系中的进化及功能意义仍有待深入研究。在此，我们从661个脊椎动物基因组中鉴定出9291个TAS2Rs。大规模系统发育基因组分析表明，青蛙和蝾螈的TAS2R基因含量异常高，这与其他脊椎动物谱系形成鲜明对比。在大多数物种中，TAS2R基因成簇存在；与其他脊椎动物相比，两栖动物有额外的基因簇，且每个基因簇中的基因更多。我们发现，尽管大多数谱系中的TAS2R总数稳定，但亲缘关系较近的物种之间，脊椎动物的TAS2Rs几乎没有一对一的直系同源基因。有趣的是，TAS2R的数量与仅在口外组织中表达的受体成正比。体外受体活性分析发现，许多两栖动物的TAS2Rs作为组织特异性化学传感器，用于检测具有生态重要性的外源性物质。
