Document Detail

Supertasting and PROP bitterness depends on more than the TAS2R38 gene.
MedLine Citation:
PMID:  18209019     Owner:  NLM     Status:  MEDLINE    
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.
John E Hayes; Linda M Bartoshuk; Judith R Kidd; Valerie B Duffy
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2008-01-21
Journal Detail:
Title:  Chemical senses     Volume:  33     ISSN:  0379-864X     ISO Abbreviation:  Chem. Senses     Publication Date:  2008 Mar 
Date Detail:
Created Date:  2008-03-12     Completed Date:  2008-06-11     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8217190     Medline TA:  Chem Senses     Country:  England    
Other Details:
Languages:  eng     Pagination:  255-65     Citation Subset:  IM    
Department of Nutritional Sciences, College of Agriculture and Natural Resources, University of Connecticut, Storrs, CT 06269-2101, USA.
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MeSH Terms
Amino Acid Substitution
Gene Frequency
Middle Aged
Polymorphism, Single Nucleotide*
Propylthiouracil / chemistry*
Quinine / chemistry
Receptors, G-Protein-Coupled / genetics*
Taste / genetics*,  physiology
Taste Buds / anatomy & histology,  metabolism
Taste Threshold
Tongue / anatomy & histology,  metabolism
Grant Support
Reg. No./Substance:
0/Receptors, G-Protein-Coupled; 0/taste receptors, type 2; 130-95-0/Quinine; 51-52-5/Propylthiouracil

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