• Journal of Plant Biology
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• 제34권4호
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• pp.317-323
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• 1991

Partial recovery in auxin transport capacity from inhibition by N-naphthylphthalamic acid (NPA) was observed when corn coleoptile segments were subjected to a prolonged NPA treatment. Kinetic data indicated that the recovery time is a function of the concentration of NPA applied. Desensitization to NPA was also seen in tissue slices where NPA increased net uptake of auxin, indicating that the apparant adaptation in the auxin transport system did not results possibly from auxin accumulated during transport inhibition. Studies on in vitro binding of NPA to membrane vesicles isolated from the coleoptile indicated that preincubation of the tissue with NPA resulted in the reduced binding activity. Scatchard analysis of the data indicated that this was due to decreases in the number of NPA binding sites. The possibility of causal relationship of modified NPA receptors to the sensory adaptation in auxin transport observed in coleoptile segments will be discussed.

• Journal of Photoscience
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• 제7권1호
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• pp.31-34
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• 2000

The heterotrichous ciliate Stentor coeruieus shows a step-up photophobic response to visible light In the previous paper, the existence of GTP-binding proteins was confirmed by using the antisera against the carboxy terminal decapeptide of transducin $\alpha$ subunit. The photoreceptor, stentorin, is localized in the pigment granule. If the immunoreactive G-protein directly interacts with the photoreceptor stentorin, the G-protein expected to be located in the pigment granule rather than plasma membrane. To elucidate the function of the immunoreactive G-protein, the localization of the G-protein in Stentor coeruleus was studied. The results suggest that this G-protein is located in the myoneme involved in the contraction and extension of the cell rather than in the pigment granule.

• 한국동물학회:학술대회논문집
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• 한국동물학회 1997년도 한국생물과학협회 학술발표대회
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• pp.188.1-188
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• 1997

No Abstract, See Full Text

• 한국자기공명학회:학술대회논문집
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• 한국자기공명학회 2000년도 동계총회 및 제16회 자기공명 학술발표회
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• pp.18-18
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• 2000

• 멤브레인
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• 제16권2호
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• pp.133-143
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• 2006

방사선 그라프트 중합법을 적용하여, 폴리에틸렌 다공성 중공사막에 전자선을 조사시킨 후, glycidyl methacrylate(GMA)를 그라프트 중합하였다. 그 후, 음이온 교환기로서 diethylamine (DEA), triethylamine (TEA)를 도입시켜 2종류의 음이온 교환막을 합성하였다. DEA막과 TEA막의 이온교환 밀도는 3.4 mmol/g, 1.74 mmol/g으로 DEA막이 TEA막보다 높은 이온교환기를 얻을 수 있었다. 이 2종류의 음이온교환막에 단백질(bovine serum albumin, BSA)을 투과법에 의해 고정시켜 BSA 고정막을 만들었다. DEA-BSA막의 경우, 그라프트 체인에 BSA가 8층 이상으로 다층 흡착하였으나, TEA-BSA막의 경우, 강한 음이온에 의해 다층 흡착이 이루어지지 않았다. DEA-BSA막의 경우, BSA 다층 흡착성 고정을 나타내기 때문에 L-Trp가 D-Trp보다 더 강한 흡착 특성을 나타내었다. L, D-Trp 이성질체 혼합물을 투과시킨 BTC에 있어서, DEA-BSA 막의 경우, BSA에 대한 L-Trp와 D-Trp의 키랄 인식이 다르기 때문에 2단계의 BTC곡선을 얻을 수 있었다.

• Molecules and Cells
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• 제23권1호
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• pp.1-10
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• 2007

Invading pathogens are recognized by diverse germline-encoded pattern-recognition receptors (PRRs) which are distributed in three different cellular compartments: extracellular, membrane, and cytoplasmic. In mammals, the major extracellular PRRs such as complements may first encounter the invading pathogens and opsonize them for clearance by phagocytosis which is mediated by membrane-associated phagocytic receptors including complement receptors. The major membrane-associated PRRs, Toll-like receptors, recognize diverse pathogens and generate inflammatory signals to coordinate innate immune responses and shape adaptive immune responses. Furthemore, certain membrane-associated PRRs such as Dectin-1 can mediate phagocytosis and also induce inflammatory response. When these more forefront detection systems are avoided by the pathogens, cytoplasmic PRRs may play major roles. Cytoplasmic caspase-recruiting domain (CARD) helicases such as retinoic acid-inducible protein I (RIG-I)/melanoma differentiation-associated gene 5 (MDA5), mediate antiviral immunity by inducing the production of type I interferons. Certain members of nucleotide-binding oligomerization domain (NOD)-like receptors such as NALP3 present in the cytosol form inflammasomes to induce inflammatory responses upon ligand recognition. Thus, diverse families of PRRs coordinately mediate immune responses against diverse types of pathogens.

• Journal of Nutrition and Health
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• 제28권10호
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• pp.1022-1030
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• 1995

Saponins are glycosidic compounds present in many plant foods. They are characterized by their ability to lyse cell membranes due to their surface-active properties. Saponins are believed to interact primarily with cholesterol in the cell membrane. In this study, the interaction of soybean(SS) with cell membrane was investigated using erythrocytes as a model. Mechanisms of interaction was also investigated by measuring their binding capacity with different membrane lipid fractions. Throughout the study, gypsophilla saponin(GS) and quillaja saponin(QS) were used to evaluate the membranolytic activity of soybean saponins. All saponins released hemoglobin in a concentration-dependent manner. SS induced 40% hemolysis at the concentration of 400 ppm, however there was no increase in hemoglobin release above 400ppm concentration. 5ppm of GS and 8 ppm of QS hemolyzed 100% of erythrocytes. Isolation of SS fractions by thin layer chromatography revealed that only one non-polar saponin possesses strong hemolytic activity. When saponins were incubated decreased the release of cholesterol. When the hemolytic activity of saponins was measured in the presence of other major membrane lipid components, sphingomyelin significantly reduced the hemolytic activity of SS, while cholesterol reduced the activity of QS. GS showed high affinity to other component(s) in the incubation media as well as lipids. These results suggest that the membranolytic activity of saponins are related to their specific chemical structure, which determines the interaction behavior between saponins and different membrane components, and thereby influence the biological activity.

• The Korean Journal of Physiology
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• 제25권2호
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• pp.179-188
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• 1991

Effect of a sulfhydryl reagent, p-chloromercuribenzoic acid (PCMB), on the transport of succinate was studied in brush border (BBMV) and basolateral (BLMV) membrane vesicles isolated from rabbit renal cortex. PCMB induced an irreversible inhibition of the $Na^+-dependent$ succinate uptake in a dose-dependent manner with $IC_{50}$ of 55 and $65\;{\mu}M$ in BBMV and BLMV, respectively. The inhibitory effect of PCMB was prevented by a pretreatment of vesicles with dithiothreitol. PCMB did not increase $Na^+$ permeability at concentrations inhibiting succinate uptake. The PCMB inhibition of succinate uptake was due to a change in Vmax, but not in Km. When membrane vesicles were pretreated with PCMB in the presence of unlabelled succinate, the inhibitory effect was significantly reduced. In both BBMV and BLMV, succinate uptake was inhibited by various sulfhydryl reagents with the inhibitory potency of following order: $HgCl_2$>DTNB>PCMBS>PCMB. These results suggest that sulfhydryl groups are essential for dicarboxylate transport and that they may be located at or near substrate binding sites of the transporters in renal brush border and basolateral membranes.

• Bulletin of the Korean Chemical Society
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• 제24권1호
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• pp.37-44
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• 2003

We examined the effect of polyether-type nonionic surfactants (Brij 35, Triton X-100, Tween 20 and Tween 80) on the potentiometric properties of sodium-, potassium- and calcium-selective membranes which are prepared with widely used ionophores and four kinds of polymer matrices [poly(vinyl chloride) (PVC), polyurethane (PU), PVC/PU blend, and silicone rubber (SR)]. It was found that the PVC-based membranes, which provide the best performance among all other matrix-based membranes in the absence of nonionic surfactants, exhibited larger change in their potentiometric properties when nonionic surfactants are added to the sample solution. On the other hand, the sodium-selective SR-based membrane with calix[4]arene, potassium-selective PVC/PU- or SR-based membrane with valinomycin, and the calcium-selective SR-based membrane with ETH 1001 provide almost identical analytical performance in the presence and absence of Tween 20 or Tween 80 surfactants. The origin of nonionic surfactants effect was also investigated by interpreting the experimental results obtained with various matrices and ionophores. The results suggest that the nonionic surfactant extracted into the membrane phase unselectively form complexes with the primary and interfering ions, resulting in increased background potential and lower binding ability for the ionophore. Such effects should result in deteriorated detection limits, reduced response slopes and lower selectivity for the primary ions.

• Molecules and Cells
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• 제25권1호
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• pp.7-19
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• 2008

Complexins play a critical role in the control of fast synchronous neurotransmitter release. They operate by binding to trimeric SNARE complexes consisting of the vesicle protein Synaptobrevin and the plasma membrane proteins Syntaxin and SNAP-25, which are key executors of membrane fusion reactions. SNARE complex binding by Complexins is thought to stabilize and clamp the SNARE complex in a highly fusogenic state, thereby providing a pool of readily releasable synaptic vesicles that can be released quickly and synchronously in response to an action potential and the concomitant increase in intra-synaptic $Ca^{2+}$ levels. Genetic elimination of Complexins from mammalian neurons causes a strong reduction in evoked neurotransmitter release, and altered Complexin expression levels with consequent deficits in synaptic transmission were suggested to contribute to the etiology or pathogenesis of schizophrenia, Huntington's disease, depression, bipolar disorder, Parkinson's disease, Alzheimer's disease, traumatic brain injury, Wernicke's encephalopathy, and fetal alcohol syndrome. In the present review I provide a summary of available data on the role of altered Complexin expression in brain diseases. On aggregate, the available information indicates that altered Complexin expression levels are unlikely to have a causal role in the etiology of the disorders that they have been implicated in, but that they may contribute to the corresponding symptoms.