Membrane biochemistry最新文献_第10页

Single calcium channels and their inactivation. 单钙通道及其失活。

Membrane biochemistry Pub Date : 1986-01-01 DOI: 10.3109/09687688609065444

A M Brown, D L Kunze, H D Lux

引用次数: 9

The modulatory effect of membrane viscosity on structural and functional properties of the anion exchange protein of human erythrocytes. 膜粘度对人红细胞阴离子交换蛋白结构和功能特性的调节作用。

Membrane biochemistry Pub Date : 1986-01-01 DOI: 10.3109/09687688609065449

Z I Cabantchik, D Baruch, Y Keren-Zur, M Zangvill, H Ginsburg

{"title":"The modulatory effect of membrane viscosity on structural and functional properties of the anion exchange protein of human erythrocytes.","authors":"Z I Cabantchik, D Baruch, Y Keren-Zur, M Zangvill, H Ginsburg","doi":"10.3109/09687688609065449","DOIUrl":"https://doi.org/10.3109/09687688609065449","url":null,"abstract":"The sterol content of human erythrocyte membranes was modified by polyvinylpyrrolidone (PVP)-mediated enrichment or depletion of cholesterol (CHL) or incorporation of cholesteryl hemisuccinate (CHS). The effects of these modifications on osmotic fragility and anion exchange protein (AEP) disposition and function were evaluated. CHS enrichment was fast (1 hr, 37 degrees C) and led to a concentration-dependent crenation as well as a decrease in osmotic cell fragility, in parallel with increased membrane microviscosity. CHL caused similar but considerably less marked effects due to slower incorporation rates into membranes. CHS enrichment of cells induced susceptibility of AEP to trypsin, a protease which otherwise does not affect AEP in intact cells. Although transport rates of monosaccharides, nucleosides, and anions were markedly slowed down by CHS enrichment of cells in parallel with increased membrane viscosity, anion transport was the most affected. The temperature profile of anion transport in CHS-enriched cells revealed a 10-kcal/mol increase in the enthalpy of activation relative to normal cells. Anion transport measured in heteroexchange conditions (Cl in--pyruvate out) and (Cl in-sulfate out) was relatively more susceptible to CHS modification than when it was measured in homoexchange conditions (Cl in-Cl out). The results of these measurements indicate that CHS-mediated increase in membrane viscosity affects AEP translocation capacity and transmembrane disposition via changes in lipid compressibility. Specific effects of CHS on AEP function, however, could not be ruled out.","PeriodicalId":18448,"journal":{"name":"Membrane biochemistry","volume":"6 3","pages":"197-216"},"PeriodicalIF":0.0,"publicationDate":"1986-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3109/09687688609065449","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14939767","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4

Mechanism of inhibition of calcium uptake into sarcoplasmic reticulum by notexin, a neurotoxic and myotoxic polypeptide. 神经毒性和肌毒性多肽诺特辛抑制肌浆网钙摄取的机制。

Membrane biochemistry Pub Date : 1986-01-01 DOI: 10.3109/09687688609065451

S Helmke, B D Howard

{"title":"Mechanism of inhibition of calcium uptake into sarcoplasmic reticulum by notexin, a neurotoxic and myotoxic polypeptide.","authors":"S Helmke, B D Howard","doi":"10.3109/09687688609065451","DOIUrl":"https://doi.org/10.3109/09687688609065451","url":null,"abstract":"Notexin belongs to a class of snake venom neurotoxins and myotoxins that have phospholipase A2 activity. Previous studies have shown that these toxins affect target cells differently from phospholipases that are not neurotoxic or myotoxic. Notexin inhibited the Ca2+ uptake into fragmented sarcoplasmic reticulum from rabbit skeletal muscle, but it did not cause an efflux of previously accumulated Ca2+ or inhibit the Ca2+--ATPase activity. It is suggested that notexin specifically binds to and decreases the conductance for Ca2+ of the Ca2+ pump and/or the conductance of a channel for an ion that facilitates Ca2+ transport. The K+ ionophore valinomycin reversed the notexin-induced inhibition of Ca2+ uptake into sarcoplasmic reticulum, suggesting that the molecular target of notexin could be a K+ channel. Two types of reconstitution experiments make it unlikely that notexin acts by degrading a minor lipid that is resistant to hydrolysis by nontoxic phospholipases A2. Notexin-inactivated sarcoplasmic reticulum vesicles were reactivated (with respect to Ca2+ uptake) by simple solubilization with detergent and subsequent reconstitution by detergent removal. Second, notexin was still active on sarcoplasmic reticulum vesicles after greater than 94% of the lipids were replaced by soybean phosphoglycerides during the reconstitution procedure.","PeriodicalId":18448,"journal":{"name":"Membrane biochemistry","volume":"6 3","pages":"239-53"},"PeriodicalIF":0.0,"publicationDate":"1986-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3109/09687688609065451","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14086149","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 5

Charge changes in sarcoplasmic reticulum and Ca2+-ATPase induced by calcium binding and release: a study using lipophilic ions. 钙结合和释放诱导的肌浆网和Ca2+- atp酶的电荷变化:一项使用亲脂离子的研究。

Membrane biochemistry Pub Date : 1986-01-01 DOI: 10.3109/09687688609065454

D O Levitsky, V A Loginov, A V Lebedev

{"title":"Charge changes in sarcoplasmic reticulum and Ca2+-ATPase induced by calcium binding and release: a study using lipophilic ions.","authors":"D O Levitsky, V A Loginov, A V Lebedev","doi":"10.3109/09687688609065454","DOIUrl":"https://doi.org/10.3109/09687688609065454","url":null,"abstract":"Changes in the charge of sarcoplasmic reticulum (SR) vesicles are studied using lipophilic ions, which are adsorbed by the membrane phase. Upon addition of MgATP, phenyldicarbaundecaborane (PCB-) and tetraphenylboron (TPB-) are taken up by the SR vesicles, while tetraphenylphosphonium (TPP+) is released into the water phase. The PCB- uptake occurs as well under conditions when SR membrane is shunted by high Cl- concentration. MgATP induces minor additional binding of PCB- in the presence of oxalate and it is followed by release of the lipophilic anion from the vesicles. EGTA partly reverses the ATP effect, and calcium ionophore A23187 plus EGTA reverses it completely. Vesicles that were preliminarily loaded by Ca2+ demonstrated higher passive and lower ATP-dependent PCB- binding. Activation of isolated Ca2+-ATPase in the presence of 0.1 mM EGTA results in PCB- release into the medium and additional TPP+ binding to the enzyme. We suggest that the redistribution of the lipophilic ions between the water phase and SR membrane reflects charge changes in Ca2+-binding sites inside both SR vesicles and Ca2+-ATPase molecules in the course of Ca2+ translocation.","PeriodicalId":18448,"journal":{"name":"Membrane biochemistry","volume":"6 4","pages":"291-307"},"PeriodicalIF":0.0,"publicationDate":"1986-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3109/09687688609065454","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14088563","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 5

Large-conductance Ca2+-activated K+ channels in freshly dissociated smooth muscle cells. 新解离的平滑肌细胞中大电导Ca2+激活的K+通道。

Membrane biochemistry Pub Date : 1986-01-01 DOI: 10.3109/09687688609065445

J J Singer, J V Walsh

引用次数: 20

Properties of single-ion channels, as revealed by patch-clamp analysis: chairman's introduction. 膜片钳分析揭示的单离子通道的性质:主席介绍。

Membrane biochemistry Pub Date : 1986-01-01 DOI: 10.3109/09687688609065443

N Sperelakis

引用次数: 1

Blocking mechanisms of batrachotoxin-activated Na channels in artificial bilayers. 细菌毒素激活的钠离子通道在人工双层中的阻断机制。

Membrane biochemistry Pub Date : 1986-01-01 DOI: 10.3109/09687688609065446

A Uehara, E Moczydlowski

{"title":"Blocking mechanisms of batrachotoxin-activated Na channels in artificial bilayers.","authors":"A Uehara, E Moczydlowski","doi":"10.3109/09687688609065446","DOIUrl":"https://doi.org/10.3109/09687688609065446","url":null,"abstract":"The effects of various pharmacological agents that block single batrachotoxin-activated Na channels from rat muscle can be described in terms of three modes of action that correspond to at least three different binding sites. Guanidinium toxins such as tetrodotoxin, saxitoxin, and a novel polypeptide, mu-conotoxin GIIIA, act only from the extra-cellular side and induce discrete blocked states that correspond to residence times of individual toxin molecules. Such toxins apparently do not deeply penetrate the channel pore since the voltage dependence of block is insensitive to toxin charge and block is not relieved by internal Na+. Many nonspecific organic cations, including charged anesthetics, exhibit a voltage-dependent block that is enhanced by depolarization when present on the inside of the channel. This site is probably within the pore, but binding to this site is weak, as indicated by fast blockade that often appears as lowered channel conductance. A separate class of neutral and tertiary amine anesthetics such as benzocaine and procaine induce discrete closed states when added to either side of the membrane. This blocking effect can be explained by preferential binding to closed states of the channel and appears to be due to a modulation of channel gating.","PeriodicalId":18448,"journal":{"name":"Membrane biochemistry","volume":"6 2","pages":"111-47"},"PeriodicalIF":0.0,"publicationDate":"1986-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3109/09687688609065446","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13576346","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 13

Proceedings of the 1985 Membrane Biophysics Group Symposium. 1985年膜生物物理小组研讨会论文集。

Membrane biochemistry Pub Date : 1986-01-01

引用次数: 0

Single-channel recordings from two types of amiloride-sensitive epithelial Na+ channels. 两种阿米洛利敏感上皮Na+通道的单通道记录。

Membrane biochemistry Pub Date : 1986-01-01 DOI: 10.3109/09687688609065447

K L Hamilton, D C Eaton

{"title":"Single-channel recordings from two types of amiloride-sensitive epithelial Na+ channels.","authors":"K L Hamilton, D C Eaton","doi":"10.3109/09687688609065447","DOIUrl":"https://doi.org/10.3109/09687688609065447","url":null,"abstract":"We report here the first evidence in intact epithelial cells of unit conductance events from amiloride-sensitive Na+ channels. The events were observed when patch-clamp recordings were made from the apical surface of cultured epithelial kidney cells (A6). Two types of channels were observed: one with a high selectivity to Na+ and one with relatively low selectivity. The characteristics of the low-selectivity channel are as follows: single-channel conductance ranged between 7 and 10 pS (mean = 8.4 +/- 1.3), the current-voltage (I-V) relationship displayed little if any nonlinearity over a range of +/- 80 mV (with respect to the patch pipette) and the channel Na+/K+ selectivity was approximately 3-4:1. Amiloride, a cationic blocker of the channel, reduced channel mean open time and increased channel mean closed times as the voltage of the cell interior was made more negative. Amiloride induced channel flickering at increased negative potentials (intracellular potential with respect to the patch) but did not alter the single-channel conductance or the I-V relationship from that observed in control patches. The characteristics of the high-selectivity channel are: a single-channel conductance of 1-3 pS (mean = 2.8 +/- 1.2), the current-voltage relationship is markedly nonlinear with a Na+/K+ selectivity greater than 20:1. The mean open and closed times for the two types of channels are quite different, the high-selectivity channel being open only about 10% of the time while the low-selectivity channel is open about 30% of the time.","PeriodicalId":18448,"journal":{"name":"Membrane biochemistry","volume":"6 2","pages":"149-71"},"PeriodicalIF":0.0,"publicationDate":"1986-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3109/09687688609065447","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13576347","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 58

Effects of delipidation on proton translocation and ATPase activity in beef heart electron transport particles. 脱脂对牛肉心脏电子传递粒子质子移位和atp酶活性的影响。

Membrane biochemistry Pub Date : 1986-01-01 DOI: 10.3109/09687688609065457

M J Pringle, M Taber

{"title":"Effects of delipidation on proton translocation and ATPase activity in beef heart electron transport particles.","authors":"M J Pringle, M Taber","doi":"10.3109/09687688609065457","DOIUrl":"https://doi.org/10.3109/09687688609065457","url":null,"abstract":"Delipidation of beef heart electron transport particles with phospholipase A2 has been examined. When the particles were treated with the lipase and subjected to a low bovine serum albumin wash, ATPase activity was unaffected as was the lipid/protein ratio of the particles. However, energisation by ATP/Mg2+ was abolished. Furthermore, unsaturated but not saturated fatty acids discharged the steady-state ATP-driven membrane potential of control samples. When the phospholipase A2 hydrolysis products were removed, inhibition of energy-linked reactions in the lipid-depleted particles was still observed and was interpreted in terms of non-specific leaks in the vesicle membranes, and 'specific' leaks through impaired H+-ATPase complexes. ATPase activity was less susceptible to delipidation than energisation but was, nevertheless, strongly inhibited at 50 percent lipid depletion. Spin label studies indicated a decrease in the fluidity of particle membranes accompanying delipidation. Moreover, the discontinuity seen in Arrhenius plots of ATPase activity was shifted from 17 degrees C (control) to 22 degrees C at 50 percent phospholipid depletion. The data are consistent with a release of unsaturated fatty acids by phospholipase A2 rendering the transport particles both leakier and the membranes less fluid than controls.","PeriodicalId":18448,"journal":{"name":"Membrane biochemistry","volume":"6 4","pages":"347-63"},"PeriodicalIF":0.0,"publicationDate":"1986-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3109/09687688609065457","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14018224","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0