• KSBB Journal
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• v.7 no.4
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• pp.302-307
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• 1992

Protein phosphatase 2A was obtained from a cytosolic fraction of bovine brain homogenate. The phosphatase activity using phosphorylated histone Hl as substrate was suppressed in the presence of liposomes composed of dipalmitoylphosphatidylcholine(DPPC) or the mixture of phosphatidylserine and DPPC. The binding of protein phosphatase to liposome was indicated by the facts that the phosphatase activity of the supernatant of protein phosphatase/multilayer vesicle mixture was decreased with increasing amount of liposome, and that [$^{125}I$]-labeled protein phosphatase was coeluted with liposome. However, the affinity of the protein for phospholipid membrane was not so high. On the other hand, okadaic acid and liposome reduced the phosphatase activity synergistically, which means that okadaic acid binds neither to lipid membrane nor to the membrane-associated phosphatase, The inhibitory effect of liposome was, therefore, ascribed to association of the protein phosphatase 2A with the lipid bilayer membrane.

• BMB Reports
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• v.42 no.11
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• pp.697-704
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• 2009

Membrane proteins play important roles in the biology of the cell, including intercellular communication and molecular transport. Their well-established importance notwithstanding, the high-resolution structures of membrane proteins remain elusive due to difficulties in protein expression, purification and crystallization. Thus, accurate prediction of membrane protein topology can increase the understanding of membrane protein function. Here, we provide a brief review of the diverse computational methods for predicting membrane protein structure and function, including recent progress and essential bioinformatics tools. Our hope is that this review will be instructive to users studying membrane protein biology in their choice of appropriate bioinformatics methods.

• Journal of Microbiology and Biotechnology
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• v.3 no.4
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• pp.261-265
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• 1993

A sopA protein (41K) encoded by plasmid pXX288 was observed in the cytoplasm, whereas a sopB protein (37K) encoded by plasmid pXX157 was observed in the membrane fraction. Most of the sopB protein was solubilized from the crude membrane by treatment with Sarkosyl, which suggested that the protein may be located in the inner membrane. The sopA protein was precipitated at the concentration of 30 to 60% ammonium sulfate. The sedimentation profile of the crude membrane fraction showed a little difference according to culture media used, and the sopB protein existed in all fractions of inner membrane. The DNA of plasmids, pXX157, pXX300, and pXX167 co-sedimented with inner membrane fraction.

• KSBB Journal
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• v.13 no.2
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• pp.125-132
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• 1998

Protein affinity membrane was prepared via the coating of chitosan gel on the porous flat polysulfone membrane surface, followed by the immobilization f the reactive dye (Cibacron Blue 3GA) to the chitonsan gel. The maximum protein binding capacity of affinity membrane was about 70${\mu}g/cm^2$ determined by the batch adsorption experiments of human serum albumin (HSA). Using module of this membrane, the characteristics of protein chromatography were investigated through the experiments of elution and frontal chromatography of HSA. This membrane module promises as a chromatography column, since it represented a lower pressure drop and a greater reproducibility. The protein separation ratio was significantly influenced by the flow rate of mobile phase and the injection quantity of HSA. The dynamic protein binding capacity of module decreased from the equilibrium binding capacity with increasing flow rate and approached the value of 15 - 20 ${\mu}g/cm^2$ for flow rates above 6 mL/min.

• Bulletin of the Korean Chemical Society
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• v.28 no.10
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• pp.1756-1762
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• 2007

Envelope proteins of virus contain a segment of hydrophobic amino acids, called as fusion peptide, which triggers membrane fusion by insertion into membrane and perturbation of lipid bilayer structure. Potential fusion peptide sequences have been identified in the middle of L or M proteins or at the N-terminus of S protein in the envelope of human hepatitis B virus (HBV). Two 16-mer peptides representing the N-terminal fusion peptide of the S protein and the internal fusion peptide in L protein were synthesized, and their membrane disrupting activities were characterized. The internal fusion peptide in L protein showed higher activity of liposome leakage and hemolysis of human red blood cells than the N-terminal fusion peptide of S protein. Also, the membrane disrupting activity of the extracellular domain of L protein significantly increased when the internal fusion peptide region was exposed to N-terminus by the treatment of V8 protease. These results indicate that the internal fusion peptide region of L protein could activate membrane fusion when it is exposed by proteolysis.

• Journal of Microbiology
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• v.33 no.4
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• pp.278-282
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• 1995

S. epidermidis cell was fractionated into cell wall, cell membrane and cytoplasm. The cell membrane adsorbed the most abundant $\textrm{Pb}_{2+}$ per unit dry weight of the three fractions tested. Adsorption behavior of $\textrm{Pb}_{2+}$ in lipid and protein, which are the main components of the cell membrane, indicated that phosphatidylethanolamine and phosphatidylinositol having phosphoryl group and gangliosides containing carboxyl groups adsorbed much more $\textrm{Pb}_{2+}$ than triglycerides lacking any chargeable functional groups. Protein purified from cell membrane adsorbed larger amount of $\textrm{Pb}_{2+}$ than total native cell membrane or cell membrane lipid.

• BMB Reports
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• v.28 no.5
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• pp.387-391
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• 1995

In order to investigate whether phospholipase C (PLC) activity in oat celIs is regulated by Gprotein, we have characterized PLC in plasma membranes of oat tissues. To identify the purified plasma membrane, $K^+$-stimulated, $Mg^{2+}$-dependent ATPase activity was measured. The activity of ATPase was shown to be proportional to the concentration of membrane protein. To examine the PLC activity regulated by G-protein, we used the inside-out and outside-out plasma membrane mixture isolated from the oat cells. The plasma membrane mixture showed higher PLC activity than the one of the outside-out plasma membrane. This suggests that PLC activity is located at the cytoplasmic surface of plasma membrane. PLC activity in plasma membrane mixture was dependent on $Ca^{2+}$ with maximum activity at 100 ${\mu}m$ $Ca^{2+}$ and it was inhibited by 1 mM EGTA. Using Sep-pak $Accell^{TM}$ Plus QMA chromatography, we found that inositol 1,4,5-trisphosphate ($IP_3$) was produced in the presence of 10 ${\mu}m$ $Ca^{2+}$. The PLC activity in the membrane was enhanced by an activator of G-protein ($GTP{\gamma}S$) and not by an inhibitor ($GDP{\beta}S$). This indicates that a G-protein is involved in the activation of PLC in the plasma membrane of oat cells.

• BMB Reports
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• v.31 no.6
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• pp.542-547
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• 1998

The main function of adipocytes in various species is to store nutrient energy in the form of triglycerides, and this function may he closely related with hormonal signaling through the plasma membrane of adipocytes. Using SDS-PAGE, two-dimensional gel electrophoresis, and a membrane biotinylation technique, we have identified a 55KDa protein (55K protein) from the plasma membrane fraction of adipocytes, with an isoelectric point (pI) of 8.1-8.3. However, this 55K protein was not observed with a two-dimensional gel electrophoresis carried out on plasma membrane fractions prepared from the liver, heart, and kidney tissues. An analysis of the 12 amino acids sequence at the N-terminal of the 55K protein showed that it has a similar sequence to that of bovine serum albumin.

• International Journal of Industrial Entomology and Biomaterials
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• v.10 no.2
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• pp.125-129
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• 2005

Ribosome-associated membrane protein 4 (RAMP4) is a membrane protein that exposes its N-terminal hydrophilic portion on the cytoplasmic side and spans the membrane close to the C-terminal end. RAMP4 has previously been reported to belong to the set of proteins that remains associated with membrane-bound ribosomes, and controls the glycosylation of major histocompatbility complex class II-associated invariant chain. RAMP4 also may be relative to the stabilization of membrane proteins in response to stress, with other components of translocon, and molecular chaperons in ER. Application of 5'-RACE technique with specially designed primer, we cloned a 715 bp cDNA fragment which contains a 195 bp ORF, termed RAMP4. The deduced protein has 64 amino acid residues and contains a putative transmembrane-spanning domain at the COOH terminus.

• Journal of Nutrition and Health
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• v.27 no.5
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• pp.419-428
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• 1994

To investigate the effect of dietary menhaden oil on protein kinase C (PKC) activity and membrane phospholipid composition in epidermal cells, female BALB/C mice were fed either menhaden oil or corn oil with two different levels(5% or 20%) for 6 weeks. Membrane phosphatidycholine(PC) was decreased in menhaden oil-fed group. Eicosapentaenoic acid(EPA) and Docosahexaenoic acid(DHA) were only presented in the acyl chain of membrane phospholipid of menhaden oil-fed mice, so that membrane fluidity of the group could be different from the other group. Both cytosolic and membrane-associated PKC activity in epidermal cells were decreased in menhaden oil-fed mice when compare with corn oil-fed mice. Furthermore, rate of PKC transfer from cytosol to membrane in menhaden oil-fed group was not as fast as in corn oil-fed group. Based on these observations, dietary menhaden oil might act differently from other dietary fat in carcinogenesis.