• Genomics & Informatics
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• v.19 no.1
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• pp.9.1-9.5
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• 2021

Mammalian olfactory receptors are a family of G protein-coupled receptors (GPCRs) that occupy a large part of the genome. In human genes, olfactory receptors account for more than 40% of all GPCRs. Several types of GPCR structures have been identified, but there is no single olfactory receptor whose structure has been determined experimentally to date. The aim of this study was to model the interactions between an olfactory receptor and its ligands at the molecular level to provide hints on the binding modes between the OR2W1 olfactory receptor and its agonists and inverse agonists. The results demonstrated the modes of ligand binding in a three-dimensional model of OR2W1 and showed a statistically significant difference in binding affinity to the olfactory receptor between agonists and inverse agonists.

• Genomics & Informatics
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• v.19 no.2
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• pp.18.1-18.8
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• 2021

G protein–coupled receptors (GPCRs), including olfactory receptors, account for the largest group of genes in the human genome and occupy a very important position in signaling systems. Although olfactory receptors, which belong to the broader category of GPCRs, play an important role in monitoring the organism's surroundings, their actual three-dimensional structure has not yet been determined. Therefore, the specific details of the molecular interactions between the receptor and the ligand remain unclear. In this report, the interactions between human olfactory receptor 1A1 and its odorant molecules were simulated using computational methods, and we explored how the chemically simple odorant molecules activate the olfactory receptor.

• Applied Microscopy
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• v.37 no.4
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• pp.219-230
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• 2007

The morphological effects of intranasal zinc sulfate(5% solution) irrigation on the mouse olfactory epithelium and the regeneration process of olfactory receptor cells following nasal irrigation were studied with scanning and transmission electron microscope. The results were as follows: 1. The septal epithelium except some basal cells was wholly detached from the basement membrane, during the first 6 to 24 hours after 5% zinc sulfate irrigation. 2. 3 days after $ZnSO_4$ treatment, two layered septal epithelium was formed from basal cells. And microvilli were observed in the apical epithelium of newly formed olfactory epithelial cells. 3. 5 days after treatment, a lot of centrosomes and basal bodies were observed in the olfactory receptor cells, and cilia were lined up between microvilli on the apical membrane of olfactory receptor cells. And immature olfactory knob was first observed in the newly formed olfactory receptor cells. Mature olfactory knob was observed 1 week after treatment. 4. There are very many mature olfactory knobs in the olfactory receptor cells 2 weeks after intranasal zinc sulfate irrigation. These results support that treatment with 5% zinc sulfate is a good experimental model for the regeneration of mammalian nervous tissues because this method could thoroughly detach the septal epithelium. During the regeneration of olfactory receptor cells, the surface membrane of the olfactory receptor cells widen the surface with the microvilli. Then cilia, which arranged in a line, substituted for the microvilli. The part of the surface membrane with cilia protruded and finally formed the olfactory vesicle.

• Genomics & Informatics
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• v.16 no.1
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• pp.2-9
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• 2018

Olfactory receptors (ORs) in mammals are generally considered to function as chemosensors in the olfactory organs of animals. They are membrane proteins that traverse the cytoplasmic membrane seven times and work generally by coupling to heterotrimeric G protein. The OR is a G protein-coupled receptor that binds the guanine nucleotide-binding $G{\alpha}_{olf}$ subunit and the $G{\beta}{\gamma}$ dimer to recognize a wide spectrum of organic compounds in accordance with its cognate ligand. Mammalian ORs were originally identified from the olfactory epithelium of rat. However, it has been recently reported that the expression of ORs is not limited to the olfactory organ. In recent decades, they have been found to be expressed in diverse organs or tissues and even tumors in mammals. In this review, the expression and expected function of olfactory receptors that exist throughout an organism's system are discussed.

• Journal of Microbiology and Biotechnology
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• v.17 no.6
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• pp.928-933
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• 2007

Cameleon is a genetically engineered $Ca^{2+}$ sensing molecule consisting of two variants of the green fluorescent protein (GFP), calmodulin and calmodulin-binding protein, M13. HEK-293 cells stably expressing three types of cameleons, yellow cameleon-2, cameleon-3er, and cameleon-2nu, were constructed, and the expression and localization of these cameleons were confirmed by fluorescent imaging. Among the cameleons, the yellow cameleon-2 was selected for analyzing the change in $Ca^{2+}$ induced by the olfactory receptor-mediated signal transduction, because it is localized in the cytosol and binds to cytosolic $Ca^{2+}$ ions. Cells stably expressing yellow cameleon-2 were transfected with each of the test olfactory receptor genes, odr-10 and 17, and the expression of the olfactory receptor genes were examined using immunocytochenmical methods and RT-PCR. Stimulating each olfactory receptor with its specific odorant caused an increase in the intracellular $Ca^{2+}$ level, which was measured using yellow cameleon-2. These results demonstrate that yellow cameleon-2 can be conveniently used to examine the function of the olfactory receptors expressed in heterologous cells.

• Korean Journal of Ichthyology
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• v.28 no.1
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• pp.28-34
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• 2016

The anatomy and histology of the olfactory organ in Favonigobius gymnauchen was investigated using a stereo microscopy, light microscopy and scanning electron microscopy. The paired olfactory organs in the dorsal snout are set in between the upper lip and the eyes. These organs are composed of two openings (anterior nostril with a tubular structure and posterior nostril), a single olfactory cavity, two nasal sac (ethmoidal and lacrimal sacs), olfactory nerve and olfactory bulb. The distributional pattern of the sensory epithelium is a only one type (continuous type). This epithelium is made up of the receptor cell, supporting cell and basal cell. The receptor cell has a only one type (ciliated receptor cell with 3~4 cilia). The non-sensory epithelium is built of the stratified epithelial cells and has mucous openings on the surface. Such an olfactory organ in F. gymnauchen may be considered to reflect its ecological habitat as a shallow water or tidal pool in the coastal zone.

• Applied Microscopy
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• v.50
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• pp.18.1-18.7
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• 2020

The olfactory anatomy and histology of Lethenteron reissneri were researched using a stereo microscope, a light microscope, and a scanning electron microscope. As in other lampreys, it shows same characters as follows: i) a single olfactory organ, ii) a single tubular nostril, iii) a single olfactory chamber with gourd-like form, iv) a nasal valve, v) a nasopharyngeal pouch, vi) a sensory epithelium (SE) of continuous distribution, vii) a supporting cells with numerous long cilia, viii) an accessory olfactory organ. However, the description of a pseudostratified columnar layer in the SE and Non SE is a first record, not reported in sea lamprey Petromyzon marinus. In particular, both 19 to 20 lamellae in number and olfactory receptor neuron's quarter ciliary length of the knob diameter differ from those of P. marinus. From these results, it might be considered that the olfactory organ of L. reissneri shows well adaptive structure of a primitive fish to slow flowing water with gravel, pebbles, and sand and a hiding habit into sand bottom at daytime. The lamellar number and neuron's ciliary length may be a meaningful taxonomic character for the class Petromyzonida.

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.639-642
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• 2003

Olfactory receptor protein ODR10 was expressed in E.coli as fusion protein with GST and His6 Tag. Crude membrane extract of the expressed protein was coated on the surface of quartz crystal microbalance, and the interaction of the ODR10 with several odorants was examined. Although the expression level was very low, quartz crystal microbalance showed that the expressed protein interacted most strongly with diacetyl (butanedione), which is known to bind to the ODR10 protein selectively. The interaction between ODR10 and diacetyl was $5{\sim}10$ times stronger than the interaction between ODR10 and other odorants. Thus, E. coli cells expressing the olfactory receptor protein could be used as an olfactory biosensor. Also, such system could be used to test which olfactory receptor reacts specifically with which odorant molecules, since there has been no cheap and convenient way to test the interaction of olfactory receptors and odorant molecules yet.

• Applied Microscopy
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• v.48 no.1
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• pp.11-16
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• 2018

For Odontamblyopus lacepedii with small and turbid eyes, the gross structure and histology of the olfactory organ, which is important for its survival and protection of the receptor neuron in estuarial environment and its ecological habit, was investigated using a stereo, light and scanning electron microscopes. Externally, the paired olfactory organs with two nostrils are located identically on each side of the snout. These nostrils are positioned at the anterior tip of the upper lip (anterior nostril) and just below eyes covered with the epidermis (posterior nostril). Internally, this is built of an elongated olfactory chamber and two accessory nasal sacs. In histology, the olfactory chamber is elliptical in shape, and lined by the sensory epithelium and the non-sensory epithelium. The sensory epithelium of a pseudostratified layer consists of olfactory receptor neurons, supporting cells, basal cells and lymphatic cells. The non-sensory epithelium of a stratified layer has swollen stratified epithelial cells and mucous cells with acidic and neutral sulfomucin. From these results, we confirmed the olfactory organ of O. lacepedii is adapted to its ecological habit as well as its habitat with burrows at the muddy field with standing and murky waters.

• BMB Reports
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• v.45 no.11
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• pp.612-622
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• 2012

Olfactory receptors (ORs) detect volatile chemicals that lead to the initial perception of smell in the brain. The olfactory receptor (OR) is the first protein that recognizes odorants in the olfactory signal pathway and it is present in over 1,000 genes in mice. It is also the largest member of the G protein-coupled receptors (GPCRs). Most ORs are extensively expressed in the nasal olfactory epithelium where they perform the appropriate physiological functions that fit their location. However, recent whole-genome sequencing shows that ORs have been found outside of the olfactory system, suggesting that ORs may play an important role in the ectopic expression of non-chemosensory tissues. The ectopic expressions of ORs and their physiological functions have attracted more attention recently since MOR23 and testicular hOR17-4 have been found to be involved in skeletal muscle development, regeneration, and human sperm chemotaxis, respectively. When identifying additional expression profiles and functions of ORs in non-olfactory tissues, there are limitations posed by the small number of antibodies available for similar OR genes. This review presents the results of a research series that identifies ectopic expressions and functions of ORs in non-chemosensory tissues to provide insight into future research directions.