Ric-8B, an olfactory putative GTP exchange factor, amplifies signal transduction through the olfactory-specific G-protein Galphaolf.

The olfactory system is able to detect a large number of chemical structures with a remarkable sensitivity and specificity. Odorants are first detected by odorant receptors present in the cilia of olfactory neurons. The activated receptors couple to an olfactory-specific G-protein (Golf), which activates adenylyl cyclase III to produce cAMP. ...
Increased cAMP levels activate cyclic nucleotide-gated channels, causing cell membrane depolarization. Here we used yeast two-hybrid to search for potential regulators for Galphaolf. We found that Ric-8B (for resistant to inhibitors of cholinesterase), a putative GTP exchange factor, is able to interact with Galphaolf. Like Galphaolf, Ric-8B is predominantly expressed in the mature olfactory sensory neurons and also in a few regions in the brain. The highly restricted and colocalized expression patterns of Ric-8B and Galphaolf strongly indicate that Ric-8B is a functional partner for Galphaolf. Finally, we show that Ric-8B is able to potentiate Galphaolf-dependent cAMP accumulation in human embryonic kidney 293 cells and therefore may be an important component for odorant signal transduction.
Mesh Terms:
Animals, Blotting, Northern, Blotting, Western, Brain, Cell Line, Cyclic AMP, Enzyme Activation, GTP-Binding Protein alpha Subunits, Gene Expression, Guanine Nucleotide Exchange Factors, Humans, In Situ Hybridization, Mice, Mice, Inbred C57BL, Mutagenesis, Nuclear Proteins, Olfactory Mucosa, RNA, Messenger, Reverse Transcriptase Polymerase Chain Reaction, Sequence Alignment, Signal Transduction, Transfection, Two-Hybrid System Techniques, Yeasts
J. Neurosci.
Date: Apr. 13, 2005
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