G Protein βγ Complexes in Circumvallate Taste Cells Involved in Bitter Transduction
G protein βγ (Gβγ) complexes are considered to play an important role in second messenger signaling of phospholipase C (PLC). Monitoring the inositol 1,4,5-trisphosphate (IP3) response in circumvallate tissue homogenates upon stimulation with denatonium benzoate, it was demonstrated that a glutathio...
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Published in | Chemical senses Vol. 25; no. 4; pp. 413 - 421 |
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Main Authors | , , , , , |
Format | Journal Article Conference Proceeding |
Language | English |
Published |
Oxford
Oxford University Press
01.08.2000
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Subjects | |
Online Access | Get full text |
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Summary: | G protein βγ (Gβγ) complexes are considered to play an important role in second messenger signaling of phospholipase C (PLC). Monitoring the inositol 1,4,5-trisphosphate (IP3) response in circumvallate tissue homogenates upon stimulation with denatonium benzoate, it was demonstrated that a glutathione S-transferase–GRK3ct fusion protein—a Gβγ scavenger—attenuates the bitter tastant-induced second messenger reaction. Towards an identification of the Gβγ complex involved in rat bitter taste transduction, it was found that the G protein β3 subtype is specifically expressed in taste receptor cells of circumvallate papillae. Gβ3-specific antibodies blocked the denatonium benzoate-induced IP3 formation in a dose-dependent manner; the inhibitory effect was reversed by preincubation with the antigenic peptide. A less pronounced inhibition was observed using Gβ1-specific antibodies. Analyzing individual taste cells by single cell reverse transcriptase–polymerase chain reaction approaches, overlapping expression patterns for PLCβ2, Gαgust, Gβ3 and Gγ3 could be demonstrated. Furthermore, the co-expression of all profiled signal transduction components in individual taste receptor cells could be detected. These data support the concept that the denatonium benzoate-induced IP3 response is mediated by an activation of PLCβ2 via a Gβγ complex, possibly composed of Gβ3 as the predominant β subunit and Gγ3, and imply that multiple second messenger pathways may exist in individual taste receptor cells. |
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Bibliography: | istex:777AFDDDAF5057A80B86F756E9CD5412F9D394DC ark:/67375/HXZ-V45XZX00-S local:0413.gml Correspondence to be sent to: Joachim Freitag, University Stuttgart-Hohenheim, Institute of Physiology, Garbenstrasse 30, D-70593 Stuttgart, Germany. e-mail: freitag@uni-hohenheim.de PII:1464-3553 |
ISSN: | 0379-864X 1464-3553 |
DOI: | 10.1093/chemse/25.4.413 |