共查询到20条相似文献，搜索用时 31 毫秒
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Oakhill JS Steel R Chen ZP Scott JW Ling N Tam S Kemp BE 《Science (New York, N.Y.)》2011,332(6036):1433-1435
The adenosine monophosphate (AMP)-activated protein kinase (AMPK) regulates whole-body and cellular energy balance in response to energy demand and supply. AMPK is an αβγ heterotrimer activated by decreasing concentrations of adenosine triphosphate (ATP) and increasing AMP concentrations. AMPK activation depends on phosphorylation of the α catalytic subunit on threonine-172 (Thr(172)) by kinases LKB1 or CaMKKβ, and this is promoted by AMP binding to the γ subunit. AMP sustains activity by inhibiting dephosphorylation of α-Thr(172), whereas ATP promotes dephosphorylation. Adenosine diphosphate (ADP), like AMP, bound to γ sites 1 and 3 and stimulated α-Thr(172) phosphorylation. However, in contrast to AMP, ADP did not directly activate phosphorylated AMPK. In this way, both ADP/ATP and AMP/ATP ratios contribute to AMPK regulation. 相似文献
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Select members of the adenosine triphosphate (ATP)-binding cassette (ABC) transporter family couple ATP binding and hydrolysis to substrate efflux and confer multidrug resistance. We have determined the x-ray structure of MsbA in complex with magnesium, adenosine diphosphate, and inorganic vanadate (Mg.ADP.Vi) and the rough-chemotype lipopolysaccharide, Ra LPS. The structure supports a model involving a rigid-body torque of the two transmembrane domains during ATP hydrolysis and suggests a mechanism by which the nucleotide-binding domain communicates with the transmembrane domain. We propose a lipid "flip-flop" mechanism in which the sugar groups are sequestered in the chamber while the hydrophobic tails are dragged through the lipid bilayer. 相似文献
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Actin polymerization and ATP hydrolysis 总被引：18，自引：0，他引：18
F-actin is the major component of muscle thin filaments and, more generally, of the microfilaments of the dynamic, multifunctional cytoskeletal systems of nonmuscle eukaryotic cells. Polymeric F-actin is formed by reversible noncovalent self-association of monomeric G-actin. To understand the dynamics of microfilament systems in cells, the dynamics of polymerization of pure actin must be understood. The following model has emerged from recent work. During the polymerization process, adenosine 5'-triphosphate (ATP) that is bound to G-actin is hydrolyzed to adenosine 5'-diphosphate (ADP) that is bound to F-actin. The hydrolysis reaction occurs on the F-actin subsequent to the polymerization reaction in two steps: cleavage of ATP followed by the slower release of inorganic phosphate (Pi). As a result, at high rates of filament growth a transient cap of ATP-actin subunits exists at the ends of elongating filaments, and at steady state a stabilizing cap of ADP.Pi-actin subunits exists at the barbed ends of filaments. Cleavage of ATP results in a highly stable filament with bound ADP.Pi, and release of Pi destabilizes the filament. Thus these two steps of the hydrolytic reaction provide potential mechanisms for regulating the monomer-polymer transition. 相似文献
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Alonso MC Drummond DR Kain S Hoeng J Amos L Cross RA 《Science (New York, N.Y.)》2007,316(5821):120-123
Kinesin-1 is a two-headed molecular motor that walks along microtubules, with each step gated by adenosine triphosphate (ATP) binding. Existing models for the gating mechanism propose a role for the microtubule lattice. We show that unpolymerized tubulin binds to kinesin-1, causing tubulin-activated release of adenosine diphosphate (ADP). With no added nucleotide, each kinesin-1 dimer binds one tubulin heterodimer. In adenylyl-imidodiphosphate (AMP-PNP), a nonhydrolyzable ATP analog, each kinesin-1 dimer binds two tubulin heterodimers. The data reveal an ATP gate that operates independently of the microtubule lattice, by ATP-dependent release of a steric or allosteric block on the tubulin binding site of the tethered kinesin-ADP head. 相似文献
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The motor protein kinesin moves along microtubules, driven by adenosine triphosphate (ATP) hydrolysis. However, it remains unclear how kinesin converts the chemical energy into mechanical movement. We report crystal structures of monomeric kinesin KIF1A with three transition-state analogs: adenylyl imidodiphosphate (AMP-PNP), adenosine diphosphate (ADP)-vanadate, and ADP-AlFx (aluminofluoride complexes). These structures, together with known structures of the ADP-bound state and the adenylyl-(beta,gamma-methylene) diphosphate (AMP-PCP)-bound state, show that kinesin uses two microtubule-binding loops in an alternating manner to change its interaction with microtubules during the ATP hydrolysis cycle; loop L11 is extended in the AMP-PNP structure, whereas loop L12 is extended in the ADP structure. ADP-vanadate displays an intermediate structure in which a conformational change in two switch regions causes both loops to be raised from the microtubule, thus actively detaching kinesin. 相似文献
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Fate of low-molecular-weight organic phosphorus compounds in the P-rich and P-poor paddy soils 
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下载免费PDF全文 LI Bao-zhen Anna GUNINA Mostafa ZHRAN Davey L. JONES Paul W. HILL HU Ya-jun GE Ti-da WU Jin-shui 《农业科学学报》2021,20(9):2526-2534
Continuous application of organic fertilizers can cause accumulation of organic phosphorus(P) in soil, especially in the lowmolecular-weight organic phosphorus(LMWOP) forms. This organic P pool represents a potentially important source of P for both plants and microorganisms. To understand the effect of long-term fertilization(30 years)(P-rich soil) vs. fallowing(P-poor soil) on the bioavailability and fate of LMWOP in subtropical paddy soils, we determined the sorption and mineralization of 14 C-labeled adenosine, adenosine monophosphate(AMP), adenosine diphosphate(ADP), and adenosine triphosphate(ATP) in each soil. The contents of carbon, nitrogen, and P in the P-rich soil were more than two times greater than those in the P-poor soil. The mineralization rates of the LMWOP compounds were faster in the P-rich soil compared to the P-poor soil, and followed the order AMPADPATP. Using sterilized soil, all forms of adenosine-P were strongly sorbed to the solid phase and reached saturation in a short time, with the adsorbance increasing with the number of phosphate groups. We concluded that the mineralization of LMWOP compounds was repressed slightly by sorption to the solid phase, but only in the short term. Thus, LMWOP compounds serve as readily available sources of C for microorganisms, making P available for themselves as well as for the plants. However, P accumulation and the progressive saturation of the P sorption sites in highly fertile soils may increase the potential risk of P runoff. 相似文献
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The dynamics and polarity of actin filaments are controlled by a conformational change coupled to the hydrolysis of adenosine 5'-triphosphate (ATP) by a mechanism that remains to be elucidated. Actin modified to block polymerization was crystallized in the adenosine 5'-diphosphate (ADP) state, and the structure was solved to 1.54 angstrom resolution. Compared with previous ATP-actin structures from complexes with deoxyribonuclease I, profilin, and gelsolin, monomeric ADP-actin is characterized by a marked conformational change in subdomain 2. The successful crystallization of monomeric actin opens the way to future structure determinations of actin complexes with actin-binding proteins such as myosin. 相似文献
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Hsp70 of the mitochondrial matrix (mtHsp70) provides a critical driving force for the import of proteins into mitochondria. Tim44, a peripheral inner-membrane protein, tethers it to the import channel. Here, regulated interactions were found to maximize occupancy of the active, adenosine 5'-triphosphate (ATP)-bound mtHsp70 at the channel through its intrinsic high affinity for Tim44, as well as through release of adenosine diphosphate (ADP)-bound mtHsp70 from Tim44 by the cofactor Mge1. A model peptide substrate rapidly released mtHsp70 from Tim44, even in the absence of ATP hydrolysis. In vivo, the analogous interaction of translocating polypeptide would release mtHsp70 from the channel. Consistent with the ratchet model of translocation, subsequent hydrolysis of ATP would trap the polypeptide, driving import by preventing its movement back toward the cytosol. 相似文献
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Microtubule gelation-contraction: essential components and relation to slow axonal transport 总被引：8，自引：0，他引：8
R C Weisenberg J Flynn B C Gao S Awodi F Skee S R Goodman B M Riederer 《Science (New York, N.Y.)》1987,238(4830):1119-1122
Preparations of microtubule proteins isolated by assembly and disassembly undergo gelation-contraction after addition of adenosine triphosphate (ATP). A particulate fraction from these preparations that is required, along with purified tubulin, to produce ATP-dependent microtubule gelation-contraction in vitro has been isolated. The particulates exhibited microtubule-stimulated adenosine triphosphatase activity and moved slowly (about 1 micrometer per minute) along microtubule walls in the presence of ATP. The particulates contained tubulin, neurofilament, and spectrin polypeptides. The composition, solubility, and motility of the particulates are consistent with those of slow component a of axonal transport. 相似文献
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Panda S Sato TK Castrucci AM Rollag MD DeGrip WJ Hogenesch JB Provencio I Kay SA 《Science (New York, N.Y.)》2002,298(5601):2213-2216
The master circadian oscillator in the hypothalamic suprachiasmatic nucleus is entrained to the day/night cycle by retinal photoreceptors. Melanopsin (Opn4), an opsin-based photopigment, is a primary candidate for photoreceptor-mediated entrainment. To investigate the functional role of melanopsin in light resetting of the oscillator, we generated melanopsin-null mice (Opn4-/-). These mice entrain to a light/dark cycle and do not exhibit any overt defect in circadian activity rhythms under constant darkness. However, they display severely attenuated phase resetting in response to brief pulses of monochromatic light, highlighting the critical role of melanopsin in circadian photoentrainment in mammals. 相似文献
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麦角硫因抑制双孢蘑菇褐变及其与能量代谢关系 总被引：2，自引：1，他引：1
【目的】控制和降低运输与贮藏过程中的褐变是目前双孢蘑菇保鲜的重点。研究麦角硫因处理对双孢蘑菇采后褐变的抑制效果,进一步分析褐变与能量代谢关系,为控制褐变和延长其保质期提供科学依据和生产指导。【方法】对具有代表性的双孢蘑菇品种AS2796喷涂浓度为0.12 mmol·L-1的麦角硫因溶液,对照组采用超纯水处理,于4℃低温下贮藏17 d,贮藏时定期测定其褐变度、菌盖白度、丙二醛含量（MDA）和能量相关物质（ATP、ADP、AMP含量）、能荷及琥珀酸脱氢酶（SDH）、细胞色素氧化酶（CCO）、H+-ATPase、Ca2+-ATPase等线粒体呼吸代谢相关酶活性。【结果】随着贮藏时间的延长,双孢蘑菇的褐变度和MDA含量逐渐增加,菌盖白度不断下降。与对照组相比,麦角硫因处理延缓了MDA含量和褐变度的上升及菌盖白度的下降,保护了细胞膜的完整性,降低了膜脂过氧化程度,有效抑制了双孢蘑菇菌盖表面及内部组织的褐变。贮藏过程中,双孢蘑菇的ATP含量呈现出先上升后下降的趋势,且始终维持在较高水平,最低点（贮藏第17天）也高于0.6 mg·g-1。整个贮藏期间,双孢蘑菇的ADP和AMP含量逐渐上升,处理组的ATP和AMP含量显著高于对照组（P＜0.05),而ADP含量始终低于对照组。能荷值不断下降,但处理组双孢蘑菇的能荷值始终略高于对照组。表明麦角硫因处理延缓了双孢蘑菇采后ATP含量的下降,提高了ATP的利用效率,在一定程度上维持了较高的能荷水平。麦角硫因处理的双孢蘑菇SDH、H+-ATPase和Ca2+-ATPase酶活性显著高于对照组（P＜0.05),且CCO酶活性在贮藏前期（第5天）和贮藏末期（第17天）相较于对照组也有所提升,从而维持了更好的线粒体功能,保证了ATP的高效合成。【结论】麦角硫因处理明显抑制了双孢蘑菇采后褐变,且其对褐变的抑制作用与能量代谢密切相关。 相似文献
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A tight coupling between adenosine triphosphate (ATP) hydrolysis and vectorial ion transport has to be maintained by ATP-consuming ion pumps. We report two crystal structures of Ca2+-bound sarco(endo)plasmic reticulum Ca2+-adenosine triphosphatase (SERCA) at 2.6 and 2.9 angstrom resolution in complex with (i) a nonhydrolyzable ATP analog [adenosine (beta-gamma methylene)-triphosphate] and (ii) adenosine diphosphate plus aluminum fluoride. SERCA reacts with ATP by an associative mechanism mediated by two Mg2+ ions to form an aspartyl-phosphorylated intermediate state (Ca2-E1 approximately P). The conformational changes that accompany the reaction with ATP pull the transmembrane helices 1 and 2 and close a cytosolic entrance for Ca2+, thereby preventing backflow before Ca2+ is released on the other side of the membrane. 相似文献
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Healthy newborn Simmental and Black Pied calves with a normal number of platelets in bloodstream don’t have reliable dynamics
of the aggregation function of blood platelets with adenosine diphosphate, collagen, thrombin, ristocetin, epinephrine, as
well as combinations of ADP + epinephrine, ADP + collagen, and collagen + epinephrine inducers. The level of discocytes in
blood on days 1–2 was 78.5, not reliably changing until the end of the neonatal stage. In this case, the number of disco-echinocytes,
spherocytes, spheroechinocytes, and bipolar forms of platelets in the bloodstream remained stably low. Maintenance during
colostrum feeding of a low intensity of metabolism of endogenous arachidonic acid in platelets and of a low content of ATP,
ADP, actin, and myosin in them can be considered important mechanisms providing stability of platelet aggregation activity
in calves in the neonatal stage. 相似文献
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The 5'-AMP (adenosine monophosphate)-activated protein kinase (AMPK) coordinates metabolic function with energy availability by responding to changes in intracellular ATP (adenosine triphosphate) and AMP concentrations. Here, we report crystal structures at 2.9 and 2.6 A resolution for ATP- and AMP-bound forms of a core alphabetagamma adenylate-binding domain from the fission yeast AMPK homolog. ATP and AMP bind competitively to a single site in the gamma subunit, with their respective phosphate groups positioned near function-impairing mutants. Unexpectedly, ATP binds without counterions, amplifying its electrostatic effects on a critical regulatory region where all three subunits converge. 相似文献
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Adenosine monophosphate is required for the activation of glycogen phosphorylase b and for release of the inhibition of phosphorylase a by glucose. Two molecules of adenosine monophosphate (AMP) bind to symmetry related sites at the subunit interface of the phosphorylase dimer. Adenosine triphosphate (ATP) binds to the same site, but does not promote catalytic activity. The structure of glucose-inhibited phosphorylase a bound to AMP and also of the complex formed with glucose and ATP is described. Crystallographic refinement of these complexes reveals that structural changes are associated with AMP but not ATP binding. The origin of these effects can be traced to different effector binding modes exhibited by AMP and ATP, respectively. The conformational changes associated with AMP binding traverse multiple paths in the enzyme and link the effector and catalytic sites. 相似文献
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Finger TE Danilova V Barrows J Bartel DL Vigers AJ Stone L Hellekant G Kinnamon SC 《Science (New York, N.Y.)》2005,310(5753):1495-1499
Taste receptor cells detect chemicals in the oral cavity and transmit this information to taste nerves, but the neurotransmitter(s) have not been identified. We report that adenosine 5'-triphosphate (ATP) is the key neurotransmitter in this system. Genetic elimination of ionotropic purinergic receptors (P2X2 and P2X3) eliminates taste responses in the taste nerves, although the nerves remain responsive to touch, temperature, and menthol. Similarly, P2X-knockout mice show greatly reduced behavioral responses to sweeteners, glutamate, and bitter substances. Finally, stimulation of taste buds in vitro evokes release of ATP. Thus, ATP fulfils the criteria for a neurotransmitter linking taste buds to the nervous system. 相似文献
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Application of methyl jasmonate postharvest maintains the quality of Nanguo pears by regulating mitochondrial energy metabolism 下载免费PDF全文
下载免费PDF全文 The present study was conducted to investigate the effects of methyl jasmonate (MeJA) dipping treatment on mitochondrial energy metabolism and quality parameters of Nanguo pears during room temperature storage. The results showed that MeJA treatment suppressed the respiration rate and weight loss, and maintained the flesh firmness of Nanguo pears. MeJA also effectively maintained the content of ascorbic acid and titratable acidity in the fruit. Furthermore, the activities of H+-ATPase, Ca2+-ATPase, succinate dehydrogenase (SDH) and cytochrome C oxidase (CCO) of the MeJA-treated fruit were significantly higher than those of the untreated fruit. The contents of adenosine triphosphate (ATP) and adenosine diphosphate (ADP) and the energy charge were also enhanced by MeJA treatment. These results suggest that postharvest MeJA treatment could maintain the quality of Nanguo pears, in part by modulating mitochondrial energy metabolism during room temperature storage. 相似文献