• Molecules and Cells
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• v.26 no.5
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• pp.503-513
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• 2008

The vomeronasal organ (VNO) is a sensory organ that influences social and/or reproductive behavior and, in many cases, the survival of an organism. The VNO is believed to mediate responses to pheromones; however, many mechanisms of signal transduction in the VNO remain elusive. Here, we examined the expression of proteins involved in signal transduction that are found in the main olfactory system in the VNO. The localization of many signaling molecules in the VNO is quite different from those in the main olfactory system, suggesting differences in signal transduction mechanisms between these two chemosensory organs. Various signaling molecules are expressed in distinct areas of VNO sensory epithelium. Interestingly, we found the expressions of groups of these signaling molecules in glandular tissues adjacent to VNO, supporting the physiological significance of these glandular tissues. Our finding of high expression of signaling proteins in glandular tissues suggests that neurohumoral factors influence glandular tissues to modulate signaling cascades that in turn alter the responses of the VNO to hormonal status.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 2004.06a
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• pp.249-249
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• 2004

• Proceedings of the Microbiological Society of Korea Conference
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• 2000.05a
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• pp.13-17
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• 2000

• Journal of Microbiology and Biotechnology
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• v.17 no.1
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• pp.138-145
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• 2007

Anabaena sensory rhodopsin is a seven transmembrane protein that uses all-trans/13-cis retinal as a chromophore. About 22 residues in the retinal-binding pocket of microbial rhodopsins are conserved and important to control the quality of absorbing light and the function of ion transport or sensory transduction. The absorption maximum is 550 nm in the presence of all-trans retinal at dark. Here, we mutated Pro206 to Glu or Asp, of which the residue is conserved as Asp among all other microbial rhodopsins, and the absorption maximum and pKa of the proton acceptor group were measured by absorption spectroscopy at various pHs. Anabaena rhodopsin was expressed best in Escherichia coli in the absence of extra leader sequence when exogenous all-trans retinal was added. The wild-type Anabaena rhodopsin showed small absorption maximum changes between pH4 and 11. In addition, Pro206Asp showed 46 nm blue-shift at pH7.0. Pro206Glu or Asp may change the contribution to the electron distribution of the retinal that is involved in the major role of color tuning for this pigment. The critical residue Ser86 (Asp 96 position in bacteriorhodopsin: proton donor) for the pumping activity was replaced with Asp, but it did not change the proton pumping activity of Anabaena rhodopsin.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1994.04a
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• pp.82-87
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• 1994

Signal transduction through G protein-coupled receptors comprises three functional components, a receptor, a G protcin and a effector protein. Work over the last sevcral ycars has led to the characterization or virtually all of the components or these systems. what has come out or those studies is that these mechanisms of signal transduction are pervasive in nature being found in mammalian and avian species, as well as lower organisms such as yeast and slime mold. It is known that G protein-coupled receptors mediate the action of such diverse molecules such as small hormones and neurotransmitters, small peptide molecules as well as glycoprotein hormones and various sensory perceptions such as light, olfaction and most likely taste.

• Journal of Photoscience
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• v.4 no.2
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• pp.35-40
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• 1997

The sensory transduction processes of blue light in guard cells have been suggested the involvement of Ca$^{2+}$/calmodulin-dependent myosin light chain kinase (MLCK) or MLCK-like proteins. The source of Ca$^{2+}$ required for the signal transduction process was investigated in guard cell protoplasts (GCPs). The GCPs showed the typical H$^+$ pumping activity by blue light (200 $\mu$mol m$^{-2}$ s$^{-1}$) and fusicoccin (10 $\mu$M) under background red light (600 $\mu$mol m$^{-2}$ s$^{-1}$). The blue light-dependent H$^+$ pumping was not significantly affected by the externally changed Ca$^{2+}$ concentrations. The addition of 1 mM Ca$^{2+}$ in the bathing medium ratherly inhibited the H$^+$ pumping. In contrast, the blue light-dependent H$^+$ pumping was inhibited by caffeine and 2,5-di-(tert-butyl)-1,4-benzohydroquinone (BHQ), inhibitor of C$^{2+}$-ATPase in endoplasmic reticulum (ER) without inhibiting the H $^+$ pump. The inhibition by caffeine and BHQ was fully reversible. The extent of inhibition by caffeine and BHQ was larger when they were added together than when added separately. The results suggest that Ca$^{2+}$ required for the blue light-dependent H$^+$ pumping may be released from the intracellular Ca$^{2+}$ stores, probably ER in guard cells.

• Molecules and Cells
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• v.19 no.1
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• pp.149-154
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• 2005

Cyclic nucleotide-gated (CNG) channels encoded by the tax-4 and tax-2 genes are required for chemosensing and thermosensing in the nematode C. elegans. We identified a gene in the C. elegans genome, which we designated cng-1, that is highly homologous to tax-4. Partial CNG-1 protein tagged with green fluorescent protein was expressed in several sensory neurons of the amphid. We created a deletion mutant of cng-1, cng-1 (jh111), to investigate its in vivo function. The mutant worms had no detectable abnormalities in terms of their basic behavior or morphology. Whereas tax-4 and tax-2 mutants failed to respond to water-soluble or volatile chemical attractants, the cng-1 null mutant exhibited normal chemotaxis to such chemicals and a tax-4;cng-1 double mutant had a similar phenotype to tax-4 single mutants. Interestingly, cng-1 and tax-4 had a synergistic effect on brood size.

• Journal of Genetic Medicine
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• v.6 no.1
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• pp.25-37
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• 2009

Hereditary peripheral neuropathies can be categorized as hereditary motor and sensory neuropathies (HMSN), hereditary motor neuropathies (HMN), and hereditary sensory neuropathies (HSN). HMSN, HMN, and HSN are further subdivided into several subtypes. Here, we review the most recent findings in the molecular diagnosis and therapeutic strategy for hereditary peripheral neuropathies. The products of genes associated with hereditary peripheral neuropathy phenotypes are important for neuronal structure maintenance, axonal transport, nerve signal transduction, and functions related to the cellular integrity. Identifying the molecular basis of hereditary peripheral neuropathy and studying the relevant genes and their functions is important to understand the pathophysiological mechanisms of these neurodegenerative disorders, as well as the processes involved in the normal development and function of the peripheral nervous system. These advances and the better understanding of the pathogenesis of peripheral neuropathies represent a challenge for the diagnoses and managements of hereditary peripheral neuropathy patients in developing future supportive and curative therapies.

• Journal of Microbiology
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• v.44 no.3
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• pp.284-292
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• 2006

The cbb3 cytochrome c oxidase has the dual function as a terminal oxidase and oxygen sensor in the photosynthetic bacterium, Rhodobacter sphaeroides. The cbb3 oxidase forms a signal transduction pathway together with the PrrBA two-component system that controls photosynthesis gene expression in response to changes in oxygen tension in the environment. Under aerobic conditions the cbb3 oxidase generates an inhibitory signal, which shifts the equilibrium of PrrB kinase/phosphatase activities towards the phosphatase mode. Photosynthesis genes are thereby turned off under aerobic conditions. The catalytic subunit (CcoN) of the R. sphaeroides cbb3 oxidase contains five histidine residues (H2l4, B233, H303, H320, and H444) that are conserved in all CcoN subunits of the cbb3 oxidase, but not in the catalytic subunits of other members of copper-heme superfamily oxidases. H214A mutation of CcoN affected neither catalytic activity nor sensory (signaling) function of the cbb3 oxidase, whereas H320A mutation led to almost complete loss of both catalytic activity and sensory function of the cbb3 oxidase. H233V and H444A mutations brought about the partial loss of catalytic activity and sensory function of the cbb3 oxidase. Interestingly, the H303A mutant form of the cbb3 oxidase retains the catalytic function as a cytochrome c oxidase as compared to the wild-type oxidase, while it is defective in signaling function as an oxygen sensor. H303 appears to be implicated in either signal sensing or generation of the inhibitory signal to the PrrBA two-component system.

• Animal cells and systems
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• v.9 no.3
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• pp.139-144
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• 2005

The attractant (orange light) or repellent (white light) signal is transmitted from SRI (Sensory Rhodopsin I) via protein-protein interaction with its transducer Htrl (Halobacterial Transducer for Sensory Rhodopsin I) which in turn controls a cytoplasmic phospho-transfer pathway that modulates flagella motor switching in Halobacterium salinarum. Some mutations in both SRI and Htrl showed an unusual mutant phenotype called inverted signaling, in which the cell produces a repellent response to normally attractant light. Twelve mutations at the Glutamate 56 (E56) position in the second transmembrane helix of Htrl were introduced by site-specific random mutagenesis. Almost all E56 mutants showed orange-light inverted responses in pH and temperature-dependent manners except E56D and E56Y. Except for these two mutants, all mutants accelerated the $S_{373}$ decay compared to wild-type at $18^{\circ}C$. This supported that there is an interaction between SRI and the second transmembrane of Htrl. Also a structural model of Htrl based on the Tar crystal structure and the secondary structure prediction program proposed the E56 residue to be in the middle of the proton channel. The most important observation is that the E56 mutant provides the evidence that this residue is very sensitive for signal relay, which can be explained by the open and closed conformations of the channel (A and R conformations) in SRI, as was postulated by the unified conformational shuttling model for transport and signaling.