Suaeda salsa L. seedlings grown in Hoagland nutrient solution were treated with different concentrations of NaCl combined with two levels of K + (12 μmol/L and 6 mmol/L) to study the K + nutrition effect on plant g...Suaeda salsa L. seedlings grown in Hoagland nutrient solution were treated with different concentrations of NaCl combined with two levels of K + (12 μmol/L and 6 mmol/L) to study the K + nutrition effect on plant growth and leaf tonoplast V-H +-ATPase and V-H +-PPase activity. Increase of K + supply in the culture solution markedly increased the fresh weight, dry weight and K + content of S. salsa plants. Western blot analysis showed that the leaf V-H +-ATPase of S. salsa was at least composed of A,B,C,D,E and c subunits, and their expression decreased with the increase of NaCl concentration under K + starvation (12 μmol/L K +), but increased under normal K + application (6 mmol/L K +). Leaf V-H +-PPase molecular weight was about 72.6 kD and its expression increased as NaCl concentration increased under both high or low levels of K + concentration in nutrient solution. There was a positive correlation between of V-H +-ATPase or V-H +-PPase activity and the amounts of their expression. Results in this study suggest that K + nutrition plays an important role in the salt tolerance of S. salsa, and K + is involved in the regulation of V-H +-ATPase or V-H +-PPase activity under salt stress.展开更多
Eleven triazolyl substituted tetrahydrobenzofuran derivatives were synthesized in high yields as novel H＋/K＋- ATPase inhibitor via one-pot Cul-catalyzed three-component click reaction of azide, secondary amine and 3...Eleven triazolyl substituted tetrahydrobenzofuran derivatives were synthesized in high yields as novel H＋/K＋- ATPase inhibitor via one-pot Cul-catalyzed three-component click reaction of azide, secondary amine and 3-bromopropyne under mild conditions in water. Their structures were characterized by NMR, IR, ESI-MS, ele- mental analysis and single-crystal X-ray diffraction analysis. Most of the target compounds exhibited better H＋/K＋- ATPase inhibitory activity than commercial omeprazole with IC50 values less than 15 gmol＇L-~. The initial struc- ture-activity analysis suggested that the triazole substituted by cycloalkyl, aromatic ring or O-containing side-chain seemed to be beneficial for enhancing the activity.展开更多
Nine bisabolangelone reduction derivatives were synthesized and separated as potential anti-ulcer agent. Their structures were characterized by 2D NMR, IR, ESI-MS, elemental analysis and single-crystal X-ray diffracti...Nine bisabolangelone reduction derivatives were synthesized and separated as potential anti-ulcer agent. Their structures were characterized by 2D NMR, IR, ESI-MS, elemental analysis and single-crystal X-ray diffraction analysis. Preliminarily H＋/K＋-ATPase activity evaluation indicated that all the target compounds had a certain inhibitory effect, and compounds Ⅱ and IV exhibited the better inhibitory activity against H＋/K＋-ATPase than bisabolangelone and the commercial omeprazole with the IC50 of 23.21 and 65.32 pmol/L, respectively. The initial structure-activity analysis suggested that the presence of carbonyl group in six-membered ring and double bond in side-chain seemed to be necessary to the activity.展开更多
Under NaCl stress for 2 d, H+-ATPase activity increased, and H+-PPase activity decreased in the tonoplast of salt-tolerant barley ( Hordeum vulgare L. cv. 'Tanyin 2') roots. La3+ (1 mmol/L), an inhibitor of Ca...Under NaCl stress for 2 d, H+-ATPase activity increased, and H+-PPase activity decreased in the tonoplast of salt-tolerant barley ( Hordeum vulgare L. cv. 'Tanyin 2') roots. La3+ (1 mmol/L), an inhibitor of Ca2+ channel in plasma membrane, and EGTA (5 mmol/L), a Ca2+ chelator, inhibited this NaCl-induced increase in H+-ATPase activity but stimulated the H+-PPase activity. Treatment of barley roots with CaM antagonist (trifluoperazine, TFP, 20 mumol/L) also diminished the increase of H+-ATPase activity induced by NaCl. La3+, TFP or La3+ + TFP increased Na+ uptake and decreased K+ and Ca2+ uptake in barley roots under NaCl stress. These results suggested that the activation of tonoplast H+-ATPase and the regulation of Na+ and K+ uptake under NaCl stress may be related to Ca2+-CaM system.展开更多
Summary： Abnormal cholesterol metabolism is associated with an elevated risk of developing athero- sclerosis, hypertension, and diabetes etc. Na＋/K＋-ATPase was found to regulate cholesterol synthesis, distribution ...Summary： Abnormal cholesterol metabolism is associated with an elevated risk of developing athero- sclerosis, hypertension, and diabetes etc. Na＋/K＋-ATPase was found to regulate cholesterol synthesis, distribution and trafficking. This study aimed to examine the effect of high-fat diet on cholesterol me- tabolism in rats and the role of Na＋/K＋-ATPase/Src/ERK signaling pathway in the process. Forty male SD rats were evenly divided into high-fat diet group and control group at random. Animals in the former group were fed on high-fat diet for 12 weeks, and those fed on basic diet served as control. Blood lipids, including total cholesterol （TC）, triglyceride （TG）, high density lipoprotein-cholesterol （HDL-C）, and low density lipoprotein-cholesteral （LDL-C） levels, were detected at 3, 6 and 12 weeks. The ratio of cholesterol content in cytoplasm to that in cell membrane was detected in liver tissues. RT-PCR and Western blotting were used to measure the expression of lipid metabolism-associated genes （HMG-CoA reductase and SREBP-2） after 12-week high-fat diet. Na＋/K＋-ATPase/Src/ERK signaling path- way-related components （Na＋/K＋-ATPase ctl, Src-PY418 and pERK1/2） were also measured by West- ern blotting. The results showed that the serum TC, TG, and LDL-C levels were significantly higher in high-fat diet group than those in control group, while the HDL-C level was significantly lower in high-fat diet group at 6 weeks （P〈0.01）. High-fat diet led to an increase in the cholesterol content in the cytoplasm and cell membrane. The ratio of cholesterol content in cytoplasm to that in cell membrane was elevated over time. The expression of HMG-CoA reductase and SREBP-2 was significantly sup- pressed at mRNA and protein levels after 12-week high-fat diet （P〈0.05）. Moreover, high-fat diet pro- moted the expression of Na＋/K＋-ATPase α1 but suppressed the phosphorylation of Src-PY418 and ERK1/2 at 12 weeks （P〈0.05）. It was concluded that high-fat diet regulates cholesterol metabolism, and Na＋/K＋-ATPase signaling pathway is involved in the process possibly by regulating the expression of lipid metabolism-associated proteins HMG-CoA reductase and SREBP-2.展开更多
To reveal the insecticidal mechanism of terpinen-4-ol, the activity of Na＋,K＋-ATPase in insects tested were determined in vivo and in vitro. The results showed that terpinen-4-ol and its ester derivatives had strong...To reveal the insecticidal mechanism of terpinen-4-ol, the activity of Na＋,K＋-ATPase in insects tested were determined in vivo and in vitro. The results showed that terpinen-4-ol and its ester derivatives had strong contact activity to housefly and the contact toxicities of its derivatives except Z3 were all superior or equivalent to terpinen-4-ol. All the 7 compounds had strong inhibition towards activity of Na＋,K＋-ATPase. With poisoning symptom exacerbating, the inhibition rates were gradually increased. In vitro, the IC50 of terpinen-4-ol, Z1, Z2, Z4, Z5, and Z6 was 155.89, 197.98, 96.02, 121.36, 124.85, and 153.74 μg mL% respectively. There was well correlation between the LDs0 of terpinen-4-ol derivatives to housefly and the IC50 of terpinen-4-ol derivatives to Na＋,K＋-ATPase in housefly. In conclusion, Na＋,K＋-ATPase was likely the target of terpinen-4-ol against insects.展开更多
两种生态型苔草Carex morcroftii(C.moorcroftii)植物沙生型(DC)和水生型(SC)的愈伤组织对盐度具有不同的敏感性.本研究对这两种生态类型苔草愈伤组织进行盐胁迫处理.在100 mM NaCl处理下,Na^+百分比显著增加而K^+百分比降低,导致SC愈...两种生态型苔草Carex morcroftii(C.moorcroftii)植物沙生型(DC)和水生型(SC)的愈伤组织对盐度具有不同的敏感性.本研究对这两种生态类型苔草愈伤组织进行盐胁迫处理.在100 mM NaCl处理下,Na^+百分比显著增加而K^+百分比降低,导致SC愈伤组织Na^+/K^+比值急剧增加,但DC中Na^+/K^+比值与对照相比无显著性差异.8-Br-cGMP(cGMP的一种类似物)以浓度依赖性的方式影响DC和SC的元素比值.6-苯胺-5,8-喹啉二酮(Ly83583,cGMP抑制剂)可降低内源性cGMP的浓度,通过降低K+百分比、增加Na+百分比和Na^+/K^+比来消除8-Br-cGMP的作用.DC愈伤组织中,Ly83583能够降低由于NaCl导致的PM H^+-ATPase活性的增加.然而,乙二醇-双-(2-氨基乙基醚)四乙酸(EGTA,Ca^2+螯合剂)不能改变cGMP的内源性浓度.以上结果表明,Ca^2+作为cGMP的下游信号通过降低Na^+/K^+比率和提升PM H^+-ATPase活性增强苔草愈伤组织的耐盐性.展开更多
Acidic digestion is an important digestive process of marine fish.In fish stomach,two enzymes are involved in the secretion of hydrochloric acid(HCl)and proteomic digestion:H^(+)/K^(+)-ATPase and pepsinogen.However,th...Acidic digestion is an important digestive process of marine fish.In fish stomach,two enzymes are involved in the secretion of hydrochloric acid(HCl)and proteomic digestion:H^(+)/K^(+)-ATPase and pepsinogen.However,the starting of digestive function in fish is still unclear.To reveal the details of acidic digestion of turbot Scophthalmus maximus in early development,a 40 day of turbot larvae culture was conducted.The H^(+)/K^(+)-ATPase gene from the turbot S.maximus(smH^(+)/K^(+)-ATPase)was identified and characterized.Based on our previous discription on pepsinogen of turbot S.maximus,we combined pepsinogen and H^(+)/K^(+)-ATPase and analyzed the mechanism of acidic digestion in turbot.Results show that the spatial and temporal expression profiles of H^(+)/K^(+)-ATPase agreed with pepsinogen A and C in turbot,indicating a synergetic action between H^(+)/K^(+)-ATPase and pepsinogen during the acidic digestion process.In addition,the turbot juveniles showed a faster growth after the expressions of H^(+)/K^(+)-ATPase gene and pepsinogen gene,demonstrating that pepsin had a higher digestive efficiency,for which a compound diet should be provided to the fish from Day 22 onward.This study provided a reference for biology research and aquaculture of turbot and other marine fishes.展开更多
H+-K+-ATPase (HKA) is composed of two different subunits: an alpha and a beta subunit. Previous studies have shown that in the kidney gastric HKA (HKA alpha 1) predominates under normal dietary conditions while coloni...H+-K+-ATPase (HKA) is composed of two different subunits: an alpha and a beta subunit. Previous studies have shown that in the kidney gastric HKA (HKA alpha 1) predominates under normal dietary conditions while colonic HKA (HKA alpha 2) predominates under potassium depleted conditions [1]. The purpose of the current study was to elucidate the association between the beta and different alpha subunits from stomach, colon and kidney under normal and potassium depleted conditions. Black Swiss mice were fed a potassium-free diet for 2 weeks, beta subunit expression of HKA in stomach mucosae, colon mucosae and renal outer medulla was examined and compared between normal diet and potassium depleted diet. In wild type (WT) mice, the concentrations of the beta subunit under potassium deficient conditions were found significantly increased compared with normal dietary conditions in colon mucosae (8.27 ± 0.73 vs 6.62 ± 0.55 μg/μl, n = 7, p = 0.0416), whereas in cHKA (HKA alpha 2) mice colon mucosae, the concentrations of the beta subunit were statistically the same (5.05 ± 0.31 vs 4.76 ± 0.37 μg/μl, n = 13, p = 0.2833), and the concentration of the beta subunit stayed the same in renal outer medulla and stomach mucosae as well. The data indicate that potassium deficiency results in a significant increase in the levels of HKA beta subunit concentration in the colonic tissue of WT mice. The results indicate that the HKA beta subunit associates with the cHKA (HKA alpha 2) in order to mediate bicarbonate reabsorption under potassium depletion (hypokalemia)展开更多
The title compound △14,15-anhydro-24-thiocarbonylbufalin （1） was prepared by the reaction of natural product bufalin with Lawesson reagent. The crystal structure of 1, C24H3002S＇C24H3002S, was determined by single...The title compound △14,15-anhydro-24-thiocarbonylbufalin （1） was prepared by the reaction of natural product bufalin with Lawesson reagent. The crystal structure of 1, C24H3002S＇C24H3002S, was determined by single-crystal X-ray diffraction analysis. It belongs to monoclinic, space group C2, with a = 30.9845（2）, b = 6.8036（3）, c = 22.5791（15）/k, V= 4241.7（4） A3, Mr = 384.21, Z = 4, Dc= 1.204 g/cm3,μ = 1.463 mm4, F（000） = 1664, S = 1.064, R = 0.0487 and wR = 0.0645 for 4683 unique reflections, of which 3757 were observed （I 〉 2σ（/））. The asymmetric unit contains two independent molecules （ⅠandⅡ）, which are closely similar to each other except for the orientation of the lactone ring. Both conformations of I and II are in good agreement with the solution structure in methanol as indicated by 1H-NMR analysis. Due to the presence of heavy atom sulfur in the molecules, the final refinement resulted in a small Flack parameter 0.02（3）, permitting the assignments of the absolute configuration. In the solid state, intermolecular hydrogen bonds involving thiocarbonyl group in the lactone moiety and the hydroxyl groups in the steroid moiety ester linked adjacent molecules into a three-dimensional network. Compound 1 showed weak inhibition on Na＋/K＋-ATPase in contrast to the strong inhibitory activity of the parent compound bufalin, suggesting that the carbonyl group in lactone moiety and the hydroxyl group atC-14 play important roles for the inhibition of Na＋/K＊-ATPase.展开更多
AIM: Functional characterization of ATP1A2 mutations that are related to familial or sporadic hemiplegic migraine(FHM2, SHM). METHODS: cRNA of human Na+/K+-ATPase α2- and β1-subunits were injected in Xenopus laevis ...AIM: Functional characterization of ATP1A2 mutations that are related to familial or sporadic hemiplegic migraine(FHM2, SHM). METHODS: cRNA of human Na+/K+-ATPase α2- and β1-subunits were injected in Xenopus laevis oocytes. FHM2 or SHM mutations of residues located in putative α/β interaction sites or in the α2-subunit's C-terminal region were investigated. Mutants were analyzed by the twoelectrode voltage-clamp(TEVC) technique on Xenopus oocytes. Stationary K+-induced Na+/K+ pump currents were measured, and the voltage dependence of apparent K+ affinity was investigated. Transient currents were recorded as ouabain-sensitive currents in Na+ buffers to analyze kinetics and voltage-dependent presteady state charge translocations. The expression of constructs was verified by preparation of plasma membrane and total membrane fractions of cRNA-injected oocytes. RESULTS: Compared to the wild-type enzyme, the mutants G900R and E902K showed no significant dif-ferences in the voltage dependence of K+-induced currents, and analysis of the transient currents indicated that the extracellular Na+ affinity was not affected. Mutant G855R showed no pump activity detectable by TEVC. Also for L994del and Y1009X, pump currents could not be recorded. Analysis of the plasma and total membrane fractions showed that the expressed proteins were not or only minimally targeted to the plasma membrane. Whereas the mutation K1003E had no impact on K+ interaction, D999H affected the voltage dependence of K+-induced currents. Furthermore, kinetics of the transient currents was altered compared to the wild-type enzyme, and the apparent affinity for extracellular Na+ was reduced. CONCLUSION: The investigated FHM2/SHM mutations influence protein function differently depending on the structural impact of the mutated residue.展开更多
文摘Suaeda salsa L. seedlings grown in Hoagland nutrient solution were treated with different concentrations of NaCl combined with two levels of K + (12 μmol/L and 6 mmol/L) to study the K + nutrition effect on plant growth and leaf tonoplast V-H +-ATPase and V-H +-PPase activity. Increase of K + supply in the culture solution markedly increased the fresh weight, dry weight and K + content of S. salsa plants. Western blot analysis showed that the leaf V-H +-ATPase of S. salsa was at least composed of A,B,C,D,E and c subunits, and their expression decreased with the increase of NaCl concentration under K + starvation (12 μmol/L K +), but increased under normal K + application (6 mmol/L K +). Leaf V-H +-PPase molecular weight was about 72.6 kD and its expression increased as NaCl concentration increased under both high or low levels of K + concentration in nutrient solution. There was a positive correlation between of V-H +-ATPase or V-H +-PPase activity and the amounts of their expression. Results in this study suggest that K + nutrition plays an important role in the salt tolerance of S. salsa, and K + is involved in the regulation of V-H +-ATPase or V-H +-PPase activity under salt stress.
文摘Eleven triazolyl substituted tetrahydrobenzofuran derivatives were synthesized in high yields as novel H＋/K＋- ATPase inhibitor via one-pot Cul-catalyzed three-component click reaction of azide, secondary amine and 3-bromopropyne under mild conditions in water. Their structures were characterized by NMR, IR, ESI-MS, ele- mental analysis and single-crystal X-ray diffraction analysis. Most of the target compounds exhibited better H＋/K＋- ATPase inhibitory activity than commercial omeprazole with IC50 values less than 15 gmol＇L-~. The initial struc- ture-activity analysis suggested that the triazole substituted by cycloalkyl, aromatic ring or O-containing side-chain seemed to be beneficial for enhancing the activity.
基金Project supported by the National Natural Science Foundation of China （No. 30970296）, the Scientific and Technological Research Project of Hubei Provincial Department of Education （No. Q20111210）, the Doctoral Startup Foundation of China Three Gorges University （No. KJ2009B046） and the Preresearch Foundation of College of Chemistry and Life Sciences （No. HY0905）.
文摘Nine bisabolangelone reduction derivatives were synthesized and separated as potential anti-ulcer agent. Their structures were characterized by 2D NMR, IR, ESI-MS, elemental analysis and single-crystal X-ray diffraction analysis. Preliminarily H＋/K＋-ATPase activity evaluation indicated that all the target compounds had a certain inhibitory effect, and compounds Ⅱ and IV exhibited the better inhibitory activity against H＋/K＋-ATPase than bisabolangelone and the commercial omeprazole with the IC50 of 23.21 and 65.32 pmol/L, respectively. The initial structure-activity analysis suggested that the presence of carbonyl group in six-membered ring and double bond in side-chain seemed to be necessary to the activity.
文摘Under NaCl stress for 2 d, H+-ATPase activity increased, and H+-PPase activity decreased in the tonoplast of salt-tolerant barley ( Hordeum vulgare L. cv. 'Tanyin 2') roots. La3+ (1 mmol/L), an inhibitor of Ca2+ channel in plasma membrane, and EGTA (5 mmol/L), a Ca2+ chelator, inhibited this NaCl-induced increase in H+-ATPase activity but stimulated the H+-PPase activity. Treatment of barley roots with CaM antagonist (trifluoperazine, TFP, 20 mumol/L) also diminished the increase of H+-ATPase activity induced by NaCl. La3+, TFP or La3+ + TFP increased Na+ uptake and decreased K+ and Ca2+ uptake in barley roots under NaCl stress. These results suggested that the activation of tonoplast H+-ATPase and the regulation of Na+ and K+ uptake under NaCl stress may be related to Ca2+-CaM system.
基金supported by a grant from the National Natural Science Foundation of China(No.81200637)
文摘Summary： Abnormal cholesterol metabolism is associated with an elevated risk of developing athero- sclerosis, hypertension, and diabetes etc. Na＋/K＋-ATPase was found to regulate cholesterol synthesis, distribution and trafficking. This study aimed to examine the effect of high-fat diet on cholesterol me- tabolism in rats and the role of Na＋/K＋-ATPase/Src/ERK signaling pathway in the process. Forty male SD rats were evenly divided into high-fat diet group and control group at random. Animals in the former group were fed on high-fat diet for 12 weeks, and those fed on basic diet served as control. Blood lipids, including total cholesterol （TC）, triglyceride （TG）, high density lipoprotein-cholesterol （HDL-C）, and low density lipoprotein-cholesteral （LDL-C） levels, were detected at 3, 6 and 12 weeks. The ratio of cholesterol content in cytoplasm to that in cell membrane was detected in liver tissues. RT-PCR and Western blotting were used to measure the expression of lipid metabolism-associated genes （HMG-CoA reductase and SREBP-2） after 12-week high-fat diet. Na＋/K＋-ATPase/Src/ERK signaling path- way-related components （Na＋/K＋-ATPase ctl, Src-PY418 and pERK1/2） were also measured by West- ern blotting. The results showed that the serum TC, TG, and LDL-C levels were significantly higher in high-fat diet group than those in control group, while the HDL-C level was significantly lower in high-fat diet group at 6 weeks （P〈0.01）. High-fat diet led to an increase in the cholesterol content in the cytoplasm and cell membrane. The ratio of cholesterol content in cytoplasm to that in cell membrane was elevated over time. The expression of HMG-CoA reductase and SREBP-2 was significantly sup- pressed at mRNA and protein levels after 12-week high-fat diet （P〈0.05）. Moreover, high-fat diet pro- moted the expression of Na＋/K＋-ATPase α1 but suppressed the phosphorylation of Src-PY418 and ERK1/2 at 12 weeks （P〈0.05）. It was concluded that high-fat diet regulates cholesterol metabolism, and Na＋/K＋-ATPase signaling pathway is involved in the process possibly by regulating the expression of lipid metabolism-associated proteins HMG-CoA reductase and SREBP-2.
基金supported by the National Natural Science Foundation of China (30600404)
文摘To reveal the insecticidal mechanism of terpinen-4-ol, the activity of Na＋,K＋-ATPase in insects tested were determined in vivo and in vitro. The results showed that terpinen-4-ol and its ester derivatives had strong contact activity to housefly and the contact toxicities of its derivatives except Z3 were all superior or equivalent to terpinen-4-ol. All the 7 compounds had strong inhibition towards activity of Na＋,K＋-ATPase. With poisoning symptom exacerbating, the inhibition rates were gradually increased. In vitro, the IC50 of terpinen-4-ol, Z1, Z2, Z4, Z5, and Z6 was 155.89, 197.98, 96.02, 121.36, 124.85, and 153.74 μg mL% respectively. There was well correlation between the LDs0 of terpinen-4-ol derivatives to housefly and the IC50 of terpinen-4-ol derivatives to Na＋,K＋-ATPase in housefly. In conclusion, Na＋,K＋-ATPase was likely the target of terpinen-4-ol against insects.
基金Supported by the National Key Research and Development Program(No.2018YFD0901204)the Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(No.GML2019ZD0402)+3 种基金the Major Agricultural Application Technology Innovation Project of Shandong Province(No.SD2019YY011)the Qingdao National Laboratory for Marine Science and Technology(No.2018SDKJ0502-2)the China Agriculture Research System(No.CARS-47),the Major Science and Technology for Scientific and Technological Innovation Projects(Shandong)(No.2019JZZY020710)the STS Project(Nos.KFZD-SW-106,ZSSD-019,2017T3017,2019T3022)。
文摘Acidic digestion is an important digestive process of marine fish.In fish stomach,two enzymes are involved in the secretion of hydrochloric acid(HCl)and proteomic digestion:H^(+)/K^(+)-ATPase and pepsinogen.However,the starting of digestive function in fish is still unclear.To reveal the details of acidic digestion of turbot Scophthalmus maximus in early development,a 40 day of turbot larvae culture was conducted.The H^(+)/K^(+)-ATPase gene from the turbot S.maximus(smH^(+)/K^(+)-ATPase)was identified and characterized.Based on our previous discription on pepsinogen of turbot S.maximus,we combined pepsinogen and H^(+)/K^(+)-ATPase and analyzed the mechanism of acidic digestion in turbot.Results show that the spatial and temporal expression profiles of H^(+)/K^(+)-ATPase agreed with pepsinogen A and C in turbot,indicating a synergetic action between H^(+)/K^(+)-ATPase and pepsinogen during the acidic digestion process.In addition,the turbot juveniles showed a faster growth after the expressions of H^(+)/K^(+)-ATPase gene and pepsinogen gene,demonstrating that pepsin had a higher digestive efficiency,for which a compound diet should be provided to the fish from Day 22 onward.This study provided a reference for biology research and aquaculture of turbot and other marine fishes.
文摘H+-K+-ATPase (HKA) is composed of two different subunits: an alpha and a beta subunit. Previous studies have shown that in the kidney gastric HKA (HKA alpha 1) predominates under normal dietary conditions while colonic HKA (HKA alpha 2) predominates under potassium depleted conditions [1]. The purpose of the current study was to elucidate the association between the beta and different alpha subunits from stomach, colon and kidney under normal and potassium depleted conditions. Black Swiss mice were fed a potassium-free diet for 2 weeks, beta subunit expression of HKA in stomach mucosae, colon mucosae and renal outer medulla was examined and compared between normal diet and potassium depleted diet. In wild type (WT) mice, the concentrations of the beta subunit under potassium deficient conditions were found significantly increased compared with normal dietary conditions in colon mucosae (8.27 ± 0.73 vs 6.62 ± 0.55 μg/μl, n = 7, p = 0.0416), whereas in cHKA (HKA alpha 2) mice colon mucosae, the concentrations of the beta subunit were statistically the same (5.05 ± 0.31 vs 4.76 ± 0.37 μg/μl, n = 13, p = 0.2833), and the concentration of the beta subunit stayed the same in renal outer medulla and stomach mucosae as well. The data indicate that potassium deficiency results in a significant increase in the levels of HKA beta subunit concentration in the colonic tissue of WT mice. The results indicate that the HKA beta subunit associates with the cHKA (HKA alpha 2) in order to mediate bicarbonate reabsorption under potassium depletion (hypokalemia)
基金supported by the National Natural Science Foundation of China(81102518)
文摘The title compound △14,15-anhydro-24-thiocarbonylbufalin （1） was prepared by the reaction of natural product bufalin with Lawesson reagent. The crystal structure of 1, C24H3002S＇C24H3002S, was determined by single-crystal X-ray diffraction analysis. It belongs to monoclinic, space group C2, with a = 30.9845（2）, b = 6.8036（3）, c = 22.5791（15）/k, V= 4241.7（4） A3, Mr = 384.21, Z = 4, Dc= 1.204 g/cm3,μ = 1.463 mm4, F（000） = 1664, S = 1.064, R = 0.0487 and wR = 0.0645 for 4683 unique reflections, of which 3757 were observed （I 〉 2σ（/））. The asymmetric unit contains two independent molecules （ⅠandⅡ）, which are closely similar to each other except for the orientation of the lactone ring. Both conformations of I and II are in good agreement with the solution structure in methanol as indicated by 1H-NMR analysis. Due to the presence of heavy atom sulfur in the molecules, the final refinement resulted in a small Flack parameter 0.02（3）, permitting the assignments of the absolute configuration. In the solid state, intermolecular hydrogen bonds involving thiocarbonyl group in the lactone moiety and the hydroxyl groups in the steroid moiety ester linked adjacent molecules into a three-dimensional network. Compound 1 showed weak inhibition on Na＋/K＋-ATPase in contrast to the strong inhibitory activity of the parent compound bufalin, suggesting that the carbonyl group in lactone moiety and the hydroxyl group atC-14 play important roles for the inhibition of Na＋/K＊-ATPase.
基金Supported by German Research Foundation(Cluster of Excellence"Unifying Concepts in Catalysis")
文摘AIM: Functional characterization of ATP1A2 mutations that are related to familial or sporadic hemiplegic migraine(FHM2, SHM). METHODS: cRNA of human Na+/K+-ATPase α2- and β1-subunits were injected in Xenopus laevis oocytes. FHM2 or SHM mutations of residues located in putative α/β interaction sites or in the α2-subunit's C-terminal region were investigated. Mutants were analyzed by the twoelectrode voltage-clamp(TEVC) technique on Xenopus oocytes. Stationary K+-induced Na+/K+ pump currents were measured, and the voltage dependence of apparent K+ affinity was investigated. Transient currents were recorded as ouabain-sensitive currents in Na+ buffers to analyze kinetics and voltage-dependent presteady state charge translocations. The expression of constructs was verified by preparation of plasma membrane and total membrane fractions of cRNA-injected oocytes. RESULTS: Compared to the wild-type enzyme, the mutants G900R and E902K showed no significant dif-ferences in the voltage dependence of K+-induced currents, and analysis of the transient currents indicated that the extracellular Na+ affinity was not affected. Mutant G855R showed no pump activity detectable by TEVC. Also for L994del and Y1009X, pump currents could not be recorded. Analysis of the plasma and total membrane fractions showed that the expressed proteins were not or only minimally targeted to the plasma membrane. Whereas the mutation K1003E had no impact on K+ interaction, D999H affected the voltage dependence of K+-induced currents. Furthermore, kinetics of the transient currents was altered compared to the wild-type enzyme, and the apparent affinity for extracellular Na+ was reduced. CONCLUSION: The investigated FHM2/SHM mutations influence protein function differently depending on the structural impact of the mutated residue.
