• Proceedings of the Membrane Society of Korea Conference
• /
• 1998.04a
• /
• pp.31-35
• /
• 1998

1. INTRODUCTION : Recognition and binding of organic substrates by biological molecules are of vital importance in biophysics and biophysical chemistry. Most studies of the application focused on the development of biosensors, which detected reaction products generated by the binding between enzymes and substrates. Other types of biosensors in which membrane proteins (e.g., nicotinic acetylcholine receptor, auxin receptor ATPase, maltose bining protein, and glutmate receptor) were utilized as a receptor function were also developed. In the previous study[1], the shifts in membrane potential, caused by the injection of substrates into a permeation cell, were measured using immobilized glucose oxidase membranes. It was suggested that the reaction product was not the origin of the potential shifts, but the changes in the charge density in the membrane due to the binding between the enzyme and the substrates generated the potential shifts. In this study, $\gamma$-globulin was immobilized (entrapped) in a poly($\gamma$-amino acid) network, and the shifts in the membrane potential caused by the injection of some amino acids were investigated.

• Journal of Microbiology
• /
• v.33 no.3
• /
• pp.228-233
• /
• 1995

As S. epidermidis cell was fractionated into cell wall, cell membrane, and cytoplasm, the cell membrane proved to be the most efficient absorbent for lead ion. Utrasonication was effective, when the cells were treated during their exponential growth. The amount of the lead ion adsorbed in cell membrane decreased as hydrogen ion concentration of solution increased. Protein purified from the cell membrane showed higher adsorption capacity for the lead ion than peptidoglycan, teichoic acid from cell wall, or cell membrane lipid. Modification of carboxyl groups in the membrane protein with ethylenediamine and 1-ethyl-3-carbodiimide hydrochloride resulted in a considerable decrease of lead ion adsorption capability, suggesting that the main binding site for lead ion was the carboxyl groups of protein in cell membrane.

• Biomedical Science Letters
• /
• v.9 no.3
• /
• pp.159-165
• /
• 2003

Ankyrins are a ubiquitously expressed family of intracellular adaptor proteins involved in targeting diverse proteins to specialized membrane domains in both the plasma membrane and the endoplasmic reticulum. Recently, the studies with C-terminus of ankyrins have identified that ankyrin-B is capable of interacting with Hsp40 and sAnkl is capable of interacting with obscurin and titin, but the function of C-terminal domain of ankyrin-G remains unknown. To identify proteins interacting C-terminus of ankyrin-G, we used the C-terminus of ankyrin-G as a bait for a yeast two-hybrid screen of brain cDNA library. Approximately 1.33$\times$l0$^6$ transformants were screened, of which 13 positive clones were obtained as determined by activation of HIS3, ADE2 and MELl reporter genes. Sequence analyses of these 13 plasmids revealed that cDNA inserts of 13 colonies showed highly homologous to 11 genes, including 5 known (i.e., Na$^+$/K$^+$ ATPase $\beta$1, SERBPl, UTF2, cytochrome C oxidase and collagen IV $\alpha$2) and 6 unknown genes. The evaluation of the proteins that emerge from these experiments provides a rational approach to investigate the those proteins significant in interaction with ankyrin-G.

• The Korean Journal of Zoology
• /
• v.26 no.3
• /
• pp.155-170
• /
• 1983

The primary concern has been focused on the response and adaptation of mouse fibroblast tumor cells to heat-shock in the level of membrane surface proteins, using two labeling techniques, lactoperoxidase-catalyzed iodination and galactose oxidase-sodium borohydride. Cells arrested in $G_1$ phase exhibited the highest level of LETS protein and high molecular proteins than did cells passing through $G_1/S, S, G_2$ and M, and unsynchronized cells. Confluent cells were found to show an increase in 125K proteins and a decrease in 130K and 100K proteins selectively. The adaptation processes of tumor cells after heat-shock were observed. All the proteins above 80K were reduced immediately after heat-shock, whereas 70K protein increased markedly 24 hours after heat-shock. The 70K protein and high molecular proteins returned to normal level in 48 hours. The 70K protein was found to be trypsin-sensitive and was similarly labeled by galactose-oxidase as well as by lactoperoxidase. It was, therefore, concluded that 70K protein is glycoprotein located on the surface membrane and might be the HSP 70. Possible function of heat-shock protein on the surface membrane and the relation of this protein to differential heat-sensitivity of tumor cells are discussed.

• Korean Journal of Veterinary Research
• /
• v.29 no.4
• /
• pp.445-455
• /
• 1989

The proteins of the ruminant erythrocyte membranes were analysed by polyacrylamide gel electrophoresis in sodium dodecyl sulfate, and their relations to the slow erythrocyte sedimentation rate(ESR) of the ruminants were investigated by treating the erythrocytes with proteinases such as trypsin, chymotrypsin and pronase, and glycosidases such as neuraminidase and galactosidase. Protein content in the erythrocyte membrane was $2.85{\pm}0.28$ in human, $3.60{\pm}0.41$ in Korean cattle, $3.71{\pm}0.36$ in Holstein, $4.13{\pm}0.83$ in Korean native goat and $3.94{\pm}0.56mg/ml$ in sheep, showing higher in ruminant animals than in human(p<0.01). Although the general protein profiles of the ruminant erythrocyte membranes were almost similar to that of human, all the ruminant erythrocyte membranes showed one additional protein band, called band-Q in the previous report on proteins of bovine erythrocyte membrane, which migrated electrophoretically to the mid position between band-2 and band-3 in human erythrocyte membranes. The glycoprotein profiles of ruminant erythrocyte membranes revealed by periodic acid Schiff(PAS) stain showed a marked difference from that of human. The PAS-1(glycophorin) and PAS-2(sialoglycogrotein) present in human erythrocyte membranes were almost absent from the ruminant animals. Instead, a strong PAS-positive band near the origin of the electrophorograms, which was named as PAS-B in the previous report on proteins of bovine erythrocyte membranes, was shown in the ruminant animals except sheep. In addition, the erythrocyte membranes of Korean native goat and sheep showed a moderate PAS-negative band near the tracking dye of the electrophorograms, which was named as PAS-G in this study. In the erythrocyte treated with the enzymes, the migration of each protein fracture of erythrocyte membranes in response to each enzyme was diverse according to different species or breed of ruminant animals. Among others, band-Q present in ruminants was slightly or moderately decreased by trypsin-, chymotrypsin-, and pronase- treatments of the erythrocytes, but not only in sheep. It was particularly noticeable that PAS-B, a fraction of glycoprotein, present in ruminants except sheep, was better digested by proteinases than by glycosidases, showing remarkable increase(p<0.01) of the ESR in accord with complete digestion(disappearance) of the PAS-B band by pronase, trypsin or chymotrypsin treatment of erythrocytes. In sheep, there was almost no any response to the various enzymes in general protein and glycoprotein profiles of the erythrocyte membranes except PAS-G, which was markedly decreased by pronase treatment of the erythrocytes. Nevertheless, the ESRs were accelerated in erythrocytes treated with pronase, trypsin, chymotrypsin and neuraminidase. Erythrocyte osmotic fragility was increased in erythrocytes treated with only pronase among five enzymes in all the human and ruminant animals used in this study.

• Journal of Life Science
• /
• v.13 no.4
• /
• pp.541-550
• /
• 2003

E2 glycoprotein of hepatitis C virus (HCV) comprises a surface of viral particle together with E1 glycoprotein, and is thought to be involved in the attachment of HCV viral particle to receptor (s) on the permissible cells including hepatocytes, B cells, T cells, and monocytes. We constructed a phage library expressing cellular proteins of hepatocytes on the phage surface, which turned out to be 8.8${\times}$$10^5$ cfu of diversity and carried inserts in 95% of library. We screened both cDNA phage library and 12-mer peptide library to identify the cellular proteins binding to E2 protein. Some intracellular proteins including tensin and membrane band 4.1 which are involved in signal transduction of survival and cytoskeleton organization, were selected from cDNA phage library through several rounds of panning and screening. On the contrary, membrane proteins such as CCR7, CKR-L2, and insulin-like growth factor-1 receptor were identified through screening of peptide library. Phages expressing peptides corresponding to those membrane proteins were bound to E2 protein specifically as determined by neutralization of binding assay. Since it is well known that HCV can infect T cells as well as hepatocytes, we examined to see if E2 protein can bind to CCR7, a member of C-protein coupled receptor family expressed on T cells, using CCR7 transfected tells. Human CCR7 cDNA was cloned into pcDNA3.1(-) vector and transfected into human embryonic kidney cell, 293T, and expressed on the surface of the cell as shown by flow cytometer. Binding assay of E2 protein using CCR7 transfected cells indicated that E2 protein bound to CCR7 by dose-dependent mode, giving rise to the possibility that CCR7 might be a putative cellular receptor for HCV.

• Biomolecules & Therapeutics
• /
• v.14 no.1
• /
• pp.25-29
• /
• 2006

We tested effects of bioactive lysophospholipids including lysophosphatidic acid (LPA), lysophosphatidylcholine (LPC), sphingosylphosphorylcholine (SPC), and sphingosine I-phosphate (S1P) on membrane potential in C6 glioma cells to understand action mechanism of the lysophospholipids. Membrane potential was estimated by measuring fluorescence change of DiBAC-loaded glioma cells. LPA largely increased membrane potential and the increase was gradually diminished. LPC also increased the membrane potential, however, the increase sustained. SPC induced smaller increase of membrane potential than LPC. SIP was not able to change the membrane potential. We tested effects of suramin and pertussis toxin on lysophospholipid-induced membrane potential increase. However, there wasn't any effect. The membrane potential increase was partially diminished in $Na^+$-free media, suggesting $Na^+$ influx as a component of membrane potential changes. Thus, involvement of $Na^+$ influx in the increase of membrane potential by lysophospholipids and independence of suramin-sensitive GPCRs and pertussis toxin-sensitive G proteins are found in this study.

• Journal of Microbiology and Biotechnology
• /
• v.29 no.1
• /
• pp.1-10
• /
• 2019

Gram-negative pathogens, such as Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii, pose a serious threat to public health worldwide, due to high rates of antibiotic resistance and the lack of development of novel antimicrobial agents targeting Gram-negative bacteria. The outer membrane (OM) of Gram-negative bacteria is a unique architecture that acts as a potent permeability barrier against toxic molecules, such as antibiotics. The OM is composed of phospholipids, lipopolysaccharide (LPS), outer membrane ${\beta}-barrel$ proteins (OMP), and lipoproteins. These components are synthesized in the cytoplasm or in the inner membrane, and are then selectively transported to the OM by the specific transport machines, including the Lol, BAM, and Lpt pathways. In this review, we summarize recent studies on the assembly systems of OM components and analyze studies for the development of inhibitors that target these systems. These analyses show that OM assembly machines have the potential to be a novel attractive drug target of Gram-negative bacteria.

• Journal of Cancer Prevention
• /
• v.21 no.2
• /
• pp.95-103
• /
• 2016

Background: Excess energy supply induces chronic low-grade inflammation in association with oxidative stress in various tissues including intestinal epithelium. The objective of this study was to investigate the effect of high-fat diet (HFD) on intestinal cell membrane integrity and intestinal tumorigenesis in $Apc^{Min/+}$ mice. Methods: Mice were fed with either normal diet (ND) or HFD for 12 weeks. The number of intestinal tumors were counted and biomarkers of endotoxemia, oxidative stress, and inflammation were determined. Changes in intestinal integrity was measured by fluorescein isothiocyanate (FITC)-dextran penetration and membrane gap junction protein expression. Results: HFD group had significantly higher number of tumors compared to ND group (P < 0.05). Blood total antioxidant capacity was lower in HFD group, while colonic 8-hydroxy-2'-deoxyguanosine level, a marker of oxidative damage, was higher in HFD group compared to that of ND group (P < 0.05). The penetration of FITC-dextran was substantially increased in HFD group (P < 0.05) while the expressions of membrane gap junction proteins including zonula occludens-1, claudin-1, and occludin were lower in HFD group (P < 0.05) compared to those in ND group. Serum concentration of lipopolysaccharide (LPS) receptor (CD14) and colonic toll-like receptor 4 (a LPS receptor) mRNA expression were significantly higher in HFD group than in ND group (P < 0.05), suggesting that significant endotoxemia may occur in HFD group due to the increased membrane permeability. Serum interleukin-6 concentration and myeloperoxidase activity were also higher in HFD group compared to those of ND group (P < 0.05). Conclusions: HFD increases oxidative stress disrupting intestinal gap junction proteins, thereby accelerating membrane permeability endotoxemia, inflammation, and intestinal tumorigenesis.

• Korean Journal of Veterinary Research
• /
• v.29 no.1
• /
• pp.13-20
• /
• 1989

The proteins of the bovine erythrocyte membrane were analyzed by polyacrylamide gel electrophoresis in sodium dodecyl sulfate, and their relations to the slow sedimentation rate of bovine erythrocytes were investigated by treating the erythrocytes with trypsin. The erythrocyte sedimentation rates of bovine erythrocytes from Holstein and Korean native cattle were very slow compared with the human one (1/7 as slow as the human one) as reported previously. However, when human and Holstein erythrocytes were treated with trypsin (0.2 and 0.5 mg/ml) for 1 hour at ${37^{\circ}C}$, their sedimentation rates were markedly accelerated while the sedimentation rate of Korean native cattle's erythrocytes were not affected. Although the general protein profiles of the bovine erythrocyte membranes were almost similar to that of human, bovine erythrocyte membranes showed one additional protein band, called band Q in this study, which migrated electrophoretically to the mid-position between band 2 and band 3 in human erythrocyte membranes. Treatment of Holstein and human erythrocytes with trypsin caused a decrease or disapperance of the band Q from the erythrocyte membrane. Although the band Q in Korean native cattle's erythroyte membrane was decreased by trypsin treatment of the erythrocytes, the magnitude of the decrement was not so pronounced as in the case of human and Holstein erythrocytes. The glycoprotein profiles of the bovine erythrocyte membranes revealed by periodic acid-Schiff stain showed a marked difference from that of human. The PAS-1 (glycophorin) and PAS-2 (sialoglycoprotein) present in human erythrocyte membrane were almost absent from the bovine erythrocyte membranes. Instead, the bovine erythrocyte membranes showed a strong PAS-positive band near the origin of the electrophorograms, which is named as PAS-B in this study. The PAS-B band was disappered completely by the trypsin treatment of Holstein erythrocytes whereas the PAS-B band in Korean native cattle's erythrocyte membrane still remained after the trypsin treatment. The trypsin treatment of Korean native cattle's erythrocytes, however, led to the appearance of small molecular weight peptides, indicating that the high molecular weight glycoproteins were degraded by trypsin as in human and Holstein ones. These results suggest that the slow sedimentation rate of bovine erythrocytes is due in part to the presence of band Q protein fraction and PAS-B glycoprotein in the bovine erythrocytes.