Abstract
Gustducin is a transducin-like G protein selectively expressed in taste receptor cells. The alpha subunit of gustducin (alpha-gustducin) is critical for transduction of responses to bitter or sweet compounds. We identified a G-protein gamma subunit (Ggamma13) that colocalized with alpha-gustducin in taste receptor cells. Of 19 alpha-gustducin/Ggamma13-positive taste receptor cells profiled, all expressed the G protein beta3 subunit (Gbeta3); approximately 80% also expressed Gbeta1. Gustducin heterotrimers (alpha-gustducin/Gbeta1/Ggamma13) were activated by taste cell membranes plus bitter denatonium. Antibodies against Ggamma13 blocked the denatonium-induced increase of inositol trisphosphate (IP3) in taste tissue. We conclude that gustducin heterotrimers transduce responses to bitter and sweet compounds via alpha-gustducin's regulation of phosphodiesterase (PDE) and Gbetagamma's activation of phospholipase C (PLC).
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Amino Acid Sequence
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Animals
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Cloning, Molecular
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Enzyme Activation
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Epithelial Cells / chemistry
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GTP-Binding Protein beta Subunits*
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GTP-Binding Protein gamma Subunits*
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GTP-Binding Proteins / analysis
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GTP-Binding Proteins / genetics
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GTP-Binding Proteins / metabolism*
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Gene Expression Profiling
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Heterotrimeric GTP-Binding Proteins*
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Humans
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Inositol 1,4,5-Trisphosphate / metabolism*
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Isoenzymes / metabolism
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Lingual Frenum
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Mice
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Mice, Transgenic
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Molecular Sequence Data
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Phospholipase C beta
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Phosphoric Diester Hydrolases / metabolism
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Protein Binding
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Quaternary Ammonium Compounds / pharmacology*
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RNA, Messenger / analysis
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RNA, Messenger / genetics
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Sequence Alignment
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Taste / physiology*
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Taste Buds / chemistry*
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Taste Buds / cytology
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Taste Buds / enzymology
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Taste Buds / metabolism
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Transducin / analysis
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Transducin / chemistry
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Transducin / genetics
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Transducin / metabolism*
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Type C Phospholipases / metabolism
Substances
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G-protein Beta gamma
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GTP-Binding Protein beta Subunits
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GTP-Binding Protein gamma Subunits
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Isoenzymes
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Quaternary Ammonium Compounds
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RNA, Messenger
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gustducin
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Inositol 1,4,5-Trisphosphate
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Phosphoric Diester Hydrolases
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Type C Phospholipases
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PLCB3 protein, human
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Phospholipase C beta
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Plcb3 protein, mouse
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Plcb3 protein, rat
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GTP-Binding Proteins
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Heterotrimeric GTP-Binding Proteins
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Transducin
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denatonium saccharide