Supertasting and PROP bitterness depends on more than the TAS2R38 gene
Supertasting and PROP bitterness depends on more than the TAS2R38 gene
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DOI：
10.1093/chemse/bjm084
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发表时间：
2008-03-01
期刊：
影响因子：
3.5
通讯作者：
Duffy, Valerie B.
中科院分区：
文献类型：
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作者：
Hayes, John E.;Bartoshuk, Linda M.;Duffy, Valerie B.
TAS2R38基因的多态性为6-n-丙基硫脲嘧啶（PROP）和苯硫脲苦味相关的表型提供了见解。我们测试了139名女性和59名男性（年龄范围21-60岁）的TAS2R38基因型、味觉表型和真菌状乳头（FP）数量之间的关系，主要是欧洲血统。对3个多态性位点进行DNA分析，鉴定出常见的（丙氨酸-缬氨酸-异亮氨酸[AVI/AVI]、杂合子、脯氨酸-丙氨酸-缬氨酸[PAV/PAV]）和罕见的（脯氨酸-缬氨酸-异亮氨酸、丙氨酸-丙氨酸-缬氨酸、AAI）形式。PROP阈值> 0.15 mM的个体几乎全为AVI/AVI；阈值< 0.1 mM可为任意基因型。尽管中等PROP浓度（0.32,1 mM）的感知苦味与基因型的对应关系优于阈值，但PAV/PAV更难与PROP味觉测量相识别。对于AVI/AVIs，苦味从1到3.2 mM PROP的增加与TAS2R38杂合子和PAV/PAV的增加几乎平行。一些苦味增加与从舌尖标准区域取样的FP数量有关，但PROP苦味-FP关系因基因型而异。在纯合子中，FP是PROP苦味的显著决定因素；杂合子呈扁平关系。即使在统计上控制了TAS2R38基因型、FP和音调强度（非口服标准）之后，那些认为浓缩PROP更苦的人，也认为浓缩蔗糖、柠檬酸、氯化钠和奎宁的味道更苦。综上所述，尽管PROP阈值通常表现为单基因完全显性，但PROP苦味可能涉及额外的苦味受体，如一些非味觉纯合子的错误分类和浓缩PROP的苦味功能。受体表达的变异性可能解释了苦味与fp关系的减弱。PROP苦味确实与味觉感觉增强（即超级味觉）有关，但这不是由于TAS2R38多态性。
Polymorphisms in the TAS2R38 gene provide insight to phenotypes long associated 6-n-propylthiouracil (PROP) and phenylthiocarbamide bitterness. We tested relationships between TAS2R38 genotype, taste phenotype, and fungiform papillae (FP) number in 139 females and 59 males (age range 21-60 years), primarily of European ancestry. DNA was analyzed for 3 polymorphic sites, identifying common (alanine-valine-isoleucine [AVI/AVI], heterozygotes, proline-alanine-valine [PAV/PAV]) and rare (proline-valine-isoleucine, alanine-alanine-valine, AAI) forms. Individuals with PROP threshold > 0.15 mM were almost exclusively AVI/AVI; those with threshold < 0.1 mM could have any genotype. PAV/PAVs were more difficult to identify with PROP taste measures, although perceived bitterness of moderate PROP concentrations (0.32, 1 mM) had better correspondence with genotype than did threshold. For AVI/AVIs, increases in bitterness from 1 to 3.2 mM PROP nearly paralleled those of TAS2R38 heterozygotes and PAV/PAVs. Some bitterness gains were related to FP number sampled from a standard area on the tongue tip, yet the PROP bitterness-FP relationship differed across genotype. Among homozygotes, FP was a significant determinant of PROP bitterness; heterozygotes showed a flat relationship. Those tasting concentrated PROP as more bitter also tasted concentrated sucrose, citric acid, sodium chloride, and quinine as more intense, even after statistically controlling for TAS2R38 genotype, FP, and intensity of tones (nonoral standard). To summarize, although PROP threshold generally exhibited single-gene complete dominance, PROP bitterness may involve additional bitter receptors as evidenced by misclassification of some nontaster homozygotes and the bitterness functions for concentrated PROP. Variability in receptor expression may explain attenuated bitterness-FP relationships. PROP bitterness does associate with heightened taste sensations (i.e., supertasting), but this is not due to TAS2R38 polymorphisms.