期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2001
卷号：98
期号：15
页码：8868-8873
DOI：10.1073/pnas.151235798
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Biochemical and genetic studies have implicated -gustducin as a key component in the transduction of both bitter or sweet taste. Yet, -gustducin-null mice are not completely unresponsive to bitter or sweet compounds. To gain insights into how gustducin mediates responses to bitter and sweet compounds, and to elicit the nature of the gustducin-independent pathways, we generated a dominant-negative form of -gustducin and expressed it as a transgene from the -gustducin promoter in both wild-type and -gustducin-null mice. A single mutation, G352P, introduced into the C-terminal region of -gustducin critical for receptor interaction rendered the mutant protein unresponsive to activation by taste receptor, but left its other functions intact. In control experiments, expression of wild-type -gustducin as a transgene in -gustducin-null mice fully restored responsiveness to bitter and sweet compounds, formally proving that the targeted deletion of the -gustducin gene caused the taste deficits of the null mice. In contrast, transgenic expression of the G352P mutant did not restore responsiveness of the null mice to either bitter or sweet compounds. Furthermore, in the wild-type background, the mutant transgene inhibited endogenous -gustducin's interactions with taste receptors, i.e., it acted as a dominant-negative. That the mutant transgene further diminished the residual bitter and sweet taste responsiveness of the -gustducin-null mice suggests that other guanine nucleotide-binding regulatory proteins expressed in the -gustducin lineage of taste cells mediate these responses.
