• Proceedings of the PSK Conference
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• 2002.10a
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• pp.275.1-275.1
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• 2002

It has been proposed that G protein interacts with receptor via multiple interaction sites. With regard to this, C-terminus of the G${\alpha}$ subunit is clearly not the only structural determinant on the G proteins that is critical for receptor coupling selectivity, but the extreme N-terminus of Ga subunit and other structural elements were proposed to be responsible for dictating the interaction with receptors. (omitted)

• Reproductive and Developmental Biology
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• v.34 no.1
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• pp.47-53
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• 2010

Glycoprotein hormones have a common $\alpha$-subunit that is involved in the signaling pathway together with G protein, adenylcyclase and cAMP induction; however, it is an unclear how this common structure is related to hormonal action. To determine the biological functions of the COOH-terminal amino acids in the $\alpha$-subunit of these glycoprotein hormones, a tethered-molecule was constructed by fusing the $NH_2$-terminus of the $\alpha$-subunit to the COOH-terminus of the $\beta$-subunit of equine chorionic gonadotropin (eCG). The following deletion mutants were created by PCR; Ile was inserted at position 96 to form ${\Delta}96$, Lys was substituted at position 95 to form ${\Delta}95$, His was inserted at position 93 to form ${\Delta}93$ and Tyr was substituted at position 87 to form ${\Delta}87$. Each mutant was transfected into CHO-K1 cells. Tethered-wt eCG, and ${\Delta}96$, ${\Delta}95$, and ${\Delta}93$ mutants were efficiently secreted into the medium but the ${\Delta}87$ mutant was not secreted. Interestingly, the RT-PCR, real-time PCR, and northern blot analyses confirmed that the RNA was transcribed in the ${\Delta}87$ mutant. However, the ${\Delta}87$ mutant protein was not detected in the medium or the intracellular fraction of the cell lysates. The LH- and FSH-like activities of the recombinant proteins were assayed in terms of cAMP production using rat LH/CG and rat FSH receptors. The metabolic clearance rate (MCR) was determined by injecting rec-eCG (2 IU) into the tail vein. The ${\Delta}95$ and ${\Delta}93$ mutants were completely inactive in both the LH- and FSH-like activity assays. The ${\Delta}96$ mutant showed slight activity in the LH-like activity assay. In comparison to the wild type, the activity of the ${\Delta}96$ mutant in the FSH-like activity assay was the highest among all the mutants. The MCR assay in which rec-eCG was injected showed a peak at 10 min in all the treatment groups, which disappeared 4 h after injection. These results imply a direct interaction between the receptor and the COOH-terminal region of the a-subunit. The data also reveal a significant difference in the mechanism by which the eCG hormone interacts with the rLH and rFSH receptors. The COOH-terminal region of the $\alpha$-subunit is very important for the secretion and functioning of this hormone.

• Journal of Life Science
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• v.23 no.2
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• pp.319-323
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• 2013

Protein aggregation can cause diseases and hinder the production of useful recombinant proteins. The present study showed that at least three types of aggregates can be formed from tryptophan synthase ${\alpha}$-subunit (${\alpha}TS$) by varying conditions: (1) an opaque white precipitous aggregate, (2) a transparent gel-like precipitous aggregate, and (3) an unprecipitous aggregate. Macroscopically different aggregate types might suggest different mechanisms underlying aggregation processes.

• Proceedings of the Korean Biophysical Society Conference
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• 2002.06b
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• pp.32-32
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• 2002

To understand the functional roles of the neuron-specific $\beta$-subunit of large-conductance calcium-activated potassium ($BK_{Ca}$) channel, we isolate the full-length complementary DNA of $\beta$4-subunit from rat brain library and investigated its effects on the function of $\alpha$-subunit (Slo). The deduced amino acid sequence of rat $\beta$4 (r$\beta$4), 210 amino acids in length, was closely related to those of $\beta$4 subunits in other mammalian species but showed only a limited sequence homology to the other $\beta$-subunits, $\beta$1 to $\beta$3.(omitted)d)

• The Korean Journal of Pain
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• v.22 no.3
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• pp.210-215
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• 2009

Background: Several studies have indicated that a nerve injury enhances the expression of the voltage-gated calcium channel ${\alpha}2{\delta}1$ subunit (Cav ${\alpha}2{\delta}1$) in sensory neurons and the dorsal spinal cord. This study examined whether NMDA receptor activation is essential for Cav ${\alpha}2{\delta}1$-mediated tactile allodynia in Cav ${\alpha}2{\delta}1$ overexpressing transgenic mice and L5/6 spinal nerve ligated rats (SNL). These two models show similar Cav ${\alpha}2{\delta}1$ upregulation and behavioral hypersensitivity, without and with the presence of other injury factors, respectively. Methods: The transgenic (TG) mice were generated as described elsewhere (Feng et al., 2000). The left L5/6 spinal nerves in the Harlan Sprague Dawley rats were ligated tightly (SNL) to induce neuropathic pain, as described by Kim et al. (1992). Memantine 2 mg/kg (10 ul) was injected directly into the L5/6 spinal region followed by $10{\mu}l$ saline. Tactile allodynia was tested for any mechanical hypersensitivity. Results: The tactile allodynia in the SNL rats could be reversed by an intrathecal injection of memantine 2 mg/kg at 1.5 hours. The tactile allodynia in the Cav ${\alpha}2{\delta}1$ over-expressing TG mice could be reversed by an intrathecal injection of memantine 2 mg/kg at 1.5, 2.0 and 2.5 hours. Conclusions: The behavioral hypersensitivity was similar in the TG mice and nerve injury pain model, supporting the hypothesis that elevated Cav ${\alpha}2{\delta}1$ mediates similar pathways that underlie the pain states in both models. The selective activation of spinal NMDA receptors plays a key role in mediating the pain states in both the nerve-injury rats and TG mice.

• Korean Journal of Breeding Science
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• v.42 no.1
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• pp.35-39
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• 2010

Soybean proteins are widely used for human and animal feed in the world. ${\beta}$-conglycinin protein exhibits poor nutritional and food processing properties and Kunitz trypsin inhibitor (KTI) protein is a main anti-nutritional factor in soybean seed. The objective of this research was to identify the inheritance of $cgy_1$ gene and ti gene for the improvement of soybean cultivar with no KTI proteins and low amount of ${\beta}$-conglycinin. $F_2$ population was made by crossing between "Gaechuck2ho" (${\alpha}^{\prime}$-subunit present $Cgy_1Cgy_1$, KTI protein absent titi) and PI506876 (${\alpha}^{\prime}$-subunit absent $cgy_1cgy_1$, KTI protein present TiTi) parent. A total of 434 $F_2$ seeds were obtained and analyzed for the segregation of ${\alpha}^{\prime}$-subunit protein and KTI protein using SDS-PAGE. The segregation ratio of 3 : 1 for $Cgy_1$ locus (310 $Cgy_1$_ : 124 $cgy_1cgy_1$) and Ti locus (339 Ti_ : 95 titi) were observed. Segregation ratios of 9 : 3 : 3 : 1 (241 $Cgy_1$_Ti_: 69 $Cgy_1$_titi: 98 $cgy_1cgy_1$Ti_: 26 $cgy_1cgy_1titi$) between $Cgy_1$ gene and Ti gene in $F_2$ seeds were also observed (${\chi}^2= 5.367$, P = 0.10 - 0.20). This data showed that $Cgy_1$ gene was inherited independently with the Ti gene in soybean. These results will be useful in breeding program for selecting the line that does not exhibit or lacks both ${\alpha}^{\prime}$-subunit protein and KTI protein in soybean.

• Biomedical Science Letters
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• v.13 no.2
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• pp.127-133
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• 2007

Heterotrimeric GTP binding proteins (G proteins) mediate signal generated by neurotransmitter and hormones. Among all G proteins, Go is the most abundant in brain but its role in brain is not clearly understood. To determine the function of the alpha subunit of Go (Go$\alpha$), we search for the interacting partner of Go$\alpha$ in brain using yeast two-hybrid system. A resistant to inhibitor of cholinesterase (Ric-8B) was identified as a Go$\alpha$ interacting protein. We confirmed interaction between Go$\alpha$ and Ric-8b employing in vitro affinity binding assay and showed that the Ric-8b increased the function of Go$\alpha$. Our findings indicate that Ric-8b is possible guanine nucleotide exchange factor for Go$\alpha$.

• Journal of Life Science
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• v.9 no.3
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• pp.328-332
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• 1999

The effect of cations on the formation of protein aggregates was examined by in vitro refolding of mutant tryptophan synthase $\alpha$-subunit in which Pro 24 was replaced by Leu. $NH^{4+},; K{^+}; and; Na^{+}$ and no effect, but $Mg^{2+}; and; Ca^{2+}$stimulated the formation of protein aggregates in dose-dependent manner. It is suggested that $Mg^{2+} and Ca^{2+}$ may be implicated in the formation of protein aggregates in vivo.

• Biomedical Science Letters
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• v.15 no.4
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• pp.327-333
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• 2009

Heterotrimeric GTP binding proteins, G-proteins, mediate signal transduction generated by neurotransmitters and hormones. Among G-proteins, Go proteins are the most abundant in brain and classified as a member of Gi family. Ras-like protein in all tissues (Rit), one of the small GTPases, is a member of a Ras superfamily and identified as an important regulator of neuronal differentiation and cell transformation. Recently, we have reported that Rit functioned as a candidate downstream effector for alpha subunit of Go proteins ($Go{\alpha}$) and regulated neurite outgrowth triggered by $Go{\alpha}$ activation. In this study, we showed that the GTPase domain of $Go{\alpha}$ contributed to the direct interaction with Rit. We also demonstrated that $Go{\alpha}$ could lead to an increase of Rit activity suggesting that Rit play a role as a downstream effector of $Go{\alpha}$.

• Journal of Life Science
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• v.14 no.2
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• pp.252-254
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• 2004

The mutant tryptophan synthases at $\alpha$Asp$^{56}$ have low catalytic activities. The enzymes were treated with $\alpha$ and $\beta$ subunit-specific ligands in the presence of L-serine and indoline. It was shown that the cations resulted in changes of absorbance patterns among the proteins, while glycerophosphate showed similar pattern of absorbance. The glycerophosphate binds to the active site of $\alpha$ subunit so that $\alpha$Asp$^{56}$ may not be involved in the allosteric control with the active site of $\alpha$ subunit occupied by substrate. The results suggest that $\alpha$Asp$^{56}$ may playa role in the step of a series of reaction occurring without bound substrates in the active site of asubunit.