Reconstitution of phospholipid translocase activity with purified Drs2p,a type-IV P-type ATPase from budding yeast

Type-IV P-type ATPases (P4-ATPases) are putative phospholipid translocases, or flippases, that translocate specific phospholipid substrates from the exofacial to the cytosolic leaflet of membranes to generate phospholipid asymmetry. In addition, the activity of Drs2p, a P4-ATPase from Saccharomyces cerevisiae, is required for vesicle-mediated protein transport from the Golgi and endosomes, suggesting a role for phospholipid translocation in vesicle budding. Drs2p is necessary for translocation of a fluorescent phosphatidylserine analogue across purified Golgi membranes. However, a flippase activity has not been reconstituted with purified Drs2p or any other P4-ATPase, so whether these ATPases directly pump phospholipid across the membrane bilayer is unknown. Here, we show that Drs2p can catalyze phospholipid translocation directly through purification and reconstitution of this P4-ATPase into proteoliposomes. The noncatalytic subunit, Cdc50p, also was reconstituted in the proteoliposome, although at a substoichiometric concentration relative to Drs2p. In proteoliposomes containing Drs2p, a phosphatidylserine analogue was actively flipped across the liposome bilayer to the outer leaflet in the presence of Mg²⁺-ATP, whereas no activity toward the phosphatidylcholine or sphingomyelin analogues was observed. This flippase activity was mediated by Drs2p, because protein-free liposomes or proteoliposomes reconstituted with a catalytically inactive form of Drs2p showed no translocation activity. These data demonstrate for the first time the reconstitution of a flippase activity with a purified P4-ATPase.     

Ultracytochemical localization of Ca2+-ATPase activity in the middle ear mucosa of the guinea pig

Summary Ca²⁺-ATPase activity was studied ultra-cytochemically in the middle ear mucosa of the guinea pig. On electron microscopic examination, the most intense reaction was found on the microvilli. Reaction products were also observed on the cilia and around and between the secretory granules on the apical side of the cells in their secretory phase. The basolateral membranes contained few reaction products, while very little or no activity was found on the basal membrane.     

家兔输精管结扎16月睾丸功能变化及其机制的实验研究

18只日本大耳白雄兔随机分为输精管结扎组(VG)和假手术组(SOG)。术后第16月进行睾丸功能与形态学观察。结果表明:血清睾酮含量两组无明显差异(p>0.05);睾丸环-磷酸腺苷cAMP含量与血管紧张素Ⅰ转换酶(ACE)活力,Na~+,K~+-ATP酶及Mg~(++)-ATP酶比活性呈显著的正相关,两组比较,VG的cAMP含量与酶活力均明显地低于SOG;输精管结扎术后自身免疫性睾丸炎可能是睾丸生精功能抑制的重要原因。     

Immunohistochemical localization of Na+,K+-ATPase in the human endolymphatic sac

Summary The presence and distribution of the transport protein complex Na⁺,K⁺-ATPase in the human endolymphatic sac (ES) was demonstrated immunohistochemically using a monoclonal antibody directed toward the denatured catalytic subunit of Na⁺,K⁺-ATPase from lamb kidney medulla. Our findings support an active transcellular ion exchange by the ES epithelium with subsequent passive transcellular and paracellular outflow of water. The possible role of the lateral intercellular spaces in the outflow of endolymph at the level of the ES is discussed.     

Localization of Na+, K+-ATPase activity in the tegmentum vasculosum of the chick cochlea

Summary We studied the localization of Na⁺, K⁺-ATPase activity in the chick cochlea, utilizing a cytochemical method of K⁺-p-nitrophenylphosphatase (K⁺-NPPase), and found that the enzyme activity was limited to the dark cells of the tegmentum vasculosum (TV). Our present results indicate that the dark cells of the TV play an essential role in the maintenance of the ionic composition of the cochlear endolymph.     

烧伤大鼠肠道组织内Ca2+-ATPase、CGRP含量对胃肠动力功能的影响

目的研究烫伤大鼠早期肠道组织内Ca2+-ATPase、降钙素基因相关肽(calcitonin gene rdatedpeptide,CGRP)的变化,探讨该Ca2+-ATPase、CGRP含量变化与肠道推进功能的关系,进一步阐明烧伤后胃肠功能障碍的发生机制.方法选用清洁大鼠30只,采用30%烫伤大鼠模型,随机分为烫伤组、内毒素组及对照组测定烫伤后1 h大鼠胃肠推进距离及肠道组织中Ca2+-ATPase和CGRP的含量.结果烫伤及内毒素腹腔注射1 h后大鼠肠道碳素墨水推进距离为(53.00±8.88)cm和(91.00±10.22)cm,对照组为(142.00±11.11)cm,两两比较肠道碳素墨水推进距离,烫伤组和内毒素组明显缩短,差异有显著性(P＜0.001).肠道组织内Ca2+-ATPase分别为(263.8±58.30)、(244.4±105.5)和(380.5±116.7)mol/s,烫伤组及内毒素组肠道组织中Ca2+-ATPase与对照组比较,均有不同程度的降低(P＜0.05),CGRP的含量分别为(52.38±39.23)ng/mL,(20.48±23.11)ng/mL及(0.75±1.96)ng/mL,烫伤组及内毒素组肠道组织中CGRP含量均有不同程度的增高,两两比较差异有显著性(P＜0.01,P＜0.05).结论烫伤早期肠道组织CA2+-ATPase活性下降及CGRP含量的增高与肠道动力功能的减弱有着十分密切的关系.     

谈中医术语“气”的英译

谈中医术语“气”的英译江苏省海门卫校（江苏２２６１００）袁洪仁中医术语“气”的内涵较多，在中医及中西医结合等文献中有多种英译：（互）ｏ，（２）Ｖｉｔａｌｅｎｅｒｇｙ，（３）Ｖｉｔａｌ－Ｑｉ，（４）ｈ。ｌｔｈｔｅｎｅｒｓｓ，（５）ｈ。ｌｔｈｓＱｉ等。按...     

超大分子F1—ATP酶空间晶体生长预实验

ＡＴＰ合成酶是氧化磷酸化过程中催化ＡＴＰ合成的关键酶。具有催化活性的Ｆ１－ＡＴＰ酶部分高分辨率三维结构的解析，对阐明氧化磷酸化的机理具有重要意义。     

The reactivation of the proscillaridin-inhibited membrane ATPase by specific antibodies

Summary The action of proscillaridin (p.) on a partially purified Na⁺–K⁺-ATPase preparation was studied, using a linked optical enzyme assay. A half maximal ATPase inhibition was obtained with 6.3×10^–7 M p. Testing 5 additional glycosides and genins we observed a maximal suppression of the enzyme activity of up to 80%. Following the immunization of rabbits against a p.-human serum albumin complex, the antibody was shown to prevent and rapidly reverse the inhibition of the enzyme in a linear dose-dependent fashion.Supported by the Deutsche Forschungsgemeinschaft.     

Cardiac glycosides: Correlations among Na+, K+-ATPase,sodium pump and contractility in the guinea pig heart

Summary Relationships among positive inotropic response to cardiac glycosides, Na⁺,K⁺-ATPase inhibition and monovalent cation pump activities were studied using paced Langendorff preparations of guinea-pig heart. Na⁺,K⁺-ATPase activity was estimated from the initial velocity of (³H)-ouabain binding in ventricular homogenates, and cation pump activity from ouabain-sensitive ⁸⁶Rb uptake of ventricular slices. These parameters were assayed in control, ouabain- or digitoxintreated hearts either at the time of inotropic response to the cardiac glycosides or during the course of drug washout. Development and loss of the inotropic response during ouabain or digitoxin perfusion and washout was accompanied by reduction and subsequent recovery of the initial ouabain binding velocity, respectively. If homogenates from glycoside-treated hearts were incubated at 37°C for 10 min during ouabain-binding studies, the levels of binding were not different from those of control hearts, indicating a rapid dissociation of the glycosides from cardiac Na⁺,K⁺-ATPase in this species. Despite differences in the time course of the loss of inotropic responses produced by ouabain or digitoxin, the relationship between Na⁺,K⁺-ATPase inhibition and inotropic responses were similar. Inotropic responses to digitoxin during perfusion, and subsequent los during washout, also were accompanied by a reduction and subsequent recovery of ⁸⁶Rb uptake. A correlation between inhibition of cation pump activity and positive inotropy has hitherto not been demonstrated. Thus, it appears that with cardiac glycosides, a relationship exists among contractility, cardiac Na⁺,K⁺-ATPase and monovalent cation pump activities.