1996 Fiscal Year Final Research Report Summary
Molecular genetic approach for identification of sweet taste receptors
| Project/Area Number |
07457444
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Functional basic dentistry
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| Research Institution | Asahi University |
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Principal Investigator |
NINOMIYA Yuzou Sch.Dentistry Asahi University Assistant Prof., 歯学部, 助教授 (50076048)
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| Project Period (FY) |
1995 – 1996
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| Keywords | Sweet taste / Receptor proteins / Gurmarin / Congenic mice / D-phenylalanine / dpa gene |
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| Research Abstract |
Properties of taste receptors for sweet taste were electrophysiologically and genetically studied by examing sensitivity to a sweet-inhibiting peptide, gurmarin in mice. An attempt was made to isolate the gurmarin-sensitive sweet receptor proteins from the mouse tongue.
Previous studies demonstrated that the C57BL strain behaviorally showes sweet taste responses to D-phenylalanine (D-phe sweet taster) whereas the BALB strain exhibits no such sweet responses (D-phe non-sweet taster). The ability to perceive sweetness for D-phenylalanine is controlled by a single gene, dpa, on chromosome 4. The congenic line was established by a conventional method by using BALB as the inbred partner strain and C57BL as the donor strain. The gurmarin inhibition of responses of the chorda tympani nerve to various sweeteners was observed in C57BL and congenic mice but not in BALB mice. Single fiber response analysis also indicated that there exists two groups of sucrose-best fibers in C57BL and congenic mice differentiated by their gurmarin sensitivities. BALB mice possess only gurmarin-insensitive fibers. These results suggest that gurmarin-sensitive receptors for sweet taste and their specific coding channels were expressed in congenic mice by insertion of dpa+/dpa+ gene from the donor C57BL strain.
By using gurmarin as a probe, we tried to isolate gurmarin-sensitive sweet receptor proteins from the fungeform pappilla of mice. The results suggested that there are at least two proteins (mw : 78,000 and 60,000) which bind to gurmarin and specifically exist in C57BL and congenic mice but not in BALB mice. Further molecular genetic studies may determine amino acid sequences of the proteins.
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