Genetic variability in the ability to taste thiourea compounds has been studied for 80+ years. Over the last 3 decades, many studies have reported perceived intensity of concentrated propylthiouracil (PROP) associates with greater intensity from a broad range of stimuli, including non-bitter tastants, irritants, and retronasally delivered odorants. Thus, PROP phenotype has become a common measure of individual differences in orosensensation. Much, but not all, of the phenotypic variation in PROP bitterness is explained by TAS2R38 polymorphisms. While differences in PROP bitterness are clearly due to genetic variation, mechanistically it is challenging to envision how this receptor (narrowly tuned to the N-C=S moiety) relates to overall orosensory response. Here, we report data for 200+ individuals who had been genotyped for TAS2R38 and phenotyped for PROP in laboratory setting. Participants also reported the intensity of quinine, capsaicin, and sucrose on a general Labeled Magnitude Scale. Our data recapitulate earlier reports associating PROP bitterness with the intensity of the predominant qualities of sucrose, quinine, and capsaicin; however, we also find correlations between the intensities of sucrose, quinine, and capsaicin were much stronger with each other than with PROP. As expected, TAS2R38 diplotype did not associate with the intensity of sucrose, quinine, or capsaicin. The strength of PROP-capsaicin and PROP-sucrose relationships increased after grouping participants by TAS2R38 diplotype, with the greatest increases in association observed within homozygotes. Collectively, this suggests the suprathreshold intensity of PROP is a confounded phenotype that captures both genetic variation specific to N-C=S compounds and overall orosensation.

中文翻译：

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奎宁，蔗糖和辣椒素产生的主要品质与PROP苦味相关，但与TAS2R38基因型无关。

味觉硫脲化合物的能力中的遗传变异性已经研究了80多年。在过去的30年中，许多研究已经报告了浓丙硫氧嘧啶（PROP）缔合体的感知强度与来自广泛刺激物（包括无苦味的刺激物，刺激物和鼻后传递的气味剂）的更高强度。因此，PROP表型已成为衡量体感的个体差异的常用量度。TAS2R38多态性解释了PROP苦味中的很多（但不是全部）表型变异。尽管PROP苦味的差异显然是由于遗传变异引起的，但是从机械上讲，很难想象这种受体（窄调至NC = S部分）与总体口感反应之间的关系。这里，我们报告了200多个在实验室环境中对TAS2R38进行基因分型并对PROP进行表型分析的个体的数据。参与者还报告了一般标记的量表上奎宁，辣椒素和蔗糖的强度。我们的数据概括了较早的报道，指出PROP苦味与蔗糖，奎宁和辣椒素的主要品质强度有关；但是，我们也发现，蔗糖，奎宁和辣椒素的强度之间的相关性比与PROP的相关性强得多。不出所料，TAS2R38双倍型与蔗糖，奎宁或辣椒素的强度无关。通过TAS2R38双倍型对参与者进行分组后，PROP-辣椒素和PROP-蔗糖关系的强度增加，在纯合子中观察到的缔合最大。总的来说，