Abstract:
:Accurate calculations of force generated and of ATP flux, in steady isotonic contractions, are made on a simple, two-state muscle model of the sliding filament type. The objective is to illustrate the proper formulation and use of a complete and self-consistent molecular model of muscle. Otherwise, the model is not meant to be realistic. Calculations were made near equilibrium, including linear and quadratic terms in a power series expansion, and arbitrarily far from equilibrium by direct numerical solution of the appropriate differential equation in the probability of cross-bridge attachment. The results obtained from the two different methods agree where they overlap near equilibrium. The efficiency of free energy conversion is emphasized, and the relation to linear irreversible thermodynamics is pointed out.
journal_name
Proc Natl Acad Sci U S Aauthors
Chen YD,Hill TLdoi
10.1073/pnas.71.5.1982subject
Has Abstractpub_date
1974-05-01 00:00:00pages
1982-6issue
5eissn
0027-8424issn
1091-6490journal_volume
71pub_type
杂志文章abstract::Structural protein 4.1, which has crucial interactions within the spectrin-actin lattice of the human red cell membrane skeleton, also is widely distributed at diverse intracellular sites in nucleated cells. We previously showed that 4.1 is essential for assembly of functional nuclei in vitro and that the capacity of ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1934680100
更新日期:2003-09-16 00:00:00
abstract::Studies of biotic remains of polar ice caps have been limited to morphological identification of plant pollen and spores. By using sensitive molecular techniques, we now demonstrate a much greater range of detectable organisms; from 2000- and 4000-year-old ice-core samples, we obtained and characterized 120 clones tha...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.96.14.8017
更新日期:1999-07-06 00:00:00
abstract::An artificial increase of cyclic diguanylate (c-di-GMP) levels in Sinorhizobium meliloti 8530, a bacterium that does not carry known cellulose synthesis genes, leads to overproduction of a substance that binds the dyes Congo red and calcofluor. Sugar composition and methylation analyses and NMR studies identified this...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1421748112
更新日期:2015-02-17 00:00:00
abstract::Tobacco mosaic virus (TMV) was reconstituted from the RNA of a common strain (OM) and the protein of a watermelon strain of cucumber green mottle mosaic virus (CGMMV-W), which is a member of the tobamovirus group. In 0.25 M phosphate buffer at 25 degrees C, CGMMV-W protein existed mainly as 21S aggregates. When this p...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.79.19.5833
更新日期:1982-10-01 00:00:00
abstract::The ovaries of the mosquito Aedes aegypti cultured in vitro secrete material that behaves like ecdysone in a radioimmunoassay. The material was identified as alpha-ecdysone by high-resolution liquid and gas-liquid chromatography. Secretion reached a maximum 16 hr after a blood meal as shown by bioassay and direct dete...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.72.8.3255
更新日期:1975-08-01 00:00:00
abstract::Analysis of variations in the concentrations or structures of biomolecules (e.g., mRNAs, proteins, peptides, natural products) that occur either naturally or in response to environmental or genetic perturbations can provide important insight into complex biological processes. Many biological samples are mixtures that ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.96.10.5372
更新日期:1999-05-11 00:00:00
abstract::The interaction of activated Ras with Raf initiates signaling cascades that contribute to a significant percentage of human tumors, suggesting that agents that specifically disrupt this interaction might have desirable chemotherapeutic properties. We used a subtractive forward two-hybrid approach to identify small mol...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.222222699
更新日期:2002-10-29 00:00:00
abstract::Acyl-homoserine lactone (acyl-HSL) signaling is thought to mediate quorum sensing in many species of Proteobacteria. The opportunistic human pathogen Pseudomonas aeruginosa uses acyl-HSLs to regulate hundreds of genes, including many that code for extracellular virulence factors. The idea that the P. aeruginosa acyl-H...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0503728102
更新日期:2005-06-21 00:00:00
abstract::Complex gene regulatory circuits contain many interacting components. In principle, all of these components and interactions may be essential to the function of the circuit. Alternatively, some of them may be refinements to a simpler version of the circuit that improve its fitness. In this work, we have tested whether...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0602223104
更新日期:2007-11-06 00:00:00
abstract::P elements have been cloned and sequenced from Drosophila nebulosa. Their sequences have diverged less than 6% from P elements of Drosophila melanogaster. However D. nebulosa P elements have nucleotide changes that close all four open reading frames found in the D. melanogaster P element. Microinjection experiments sh...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.84.18.6491
更新日期:1987-09-01 00:00:00
abstract::Apolipoprotein E (apoE), a plasma apolipoprotein that plays a central role in lipoprotein metabolism, is localized in the senile plaques, congophilic angiopathy, and neurofibrillary tangles of Alzheimer disease. Late-onset familial and sporadic Alzheimer disease patients have an increased frequency of one of the three...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.90.17.8098
更新日期:1993-09-01 00:00:00
abstract::Scientific and engineering innovation is vital for American competitiveness, quality of life, and national security. However, too few American students, especially women, pursue these fields. Although this problem has attracted enormous attention, rigorously tested interventions outside artificial laboratory settings ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1613117114
更新日期:2017-06-06 00:00:00
abstract::A search for potent toxins that inhibit neuronal calcium channels in Drosophila melanogaster has resulted in the identification of a presynaptic neurotoxin from the venom of the hunting spider Hololena curta. Using Drosophila neuromuscular junction as an assay, presynaptic inhibitory activity was purified using gel fi...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.84.10.3506
更新日期:1987-05-01 00:00:00
abstract::Activation of the phosphatidylinositol 3-kinase (PI3K)/AKT signaling pathway is a frequent occurrence in human cancers and a major promoter of chemotherapeutic resistance. Inhibition of one downstream target in this pathway, mTORC1, has shown potential to improve chemosensitivity. However, the mechanisms and genetic m...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0804821105
更新日期:2008-08-05 00:00:00
abstract::Integral feedback control is a basic engineering strategy for ensuring that the output of a system robustly tracks its desired value independent of noise or variations in system parameters. In biological systems, it is common for the response to an extracellular stimulus to return to its prestimulus value even in the ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.97.9.4649
更新日期:2000-04-25 00:00:00
abstract::Somatic mutations can now be quantified in almost any cell type in mice carrying bacterial genes in a lambda phage shuttle vector. Mutations induced in vivo are detectable ex vivo, after packaging host-cell DNA into phage that are grown on suitable bacteria. However, the transgenic DNA differs from many host loci in s...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.90.22.10681
更新日期:1993-11-15 00:00:00
abstract::Nanobacteria-like objects evidenced at the surface of the orthopyroxenes of the Tataouine meteorite in South Tunisia have been studied by scanning and transmission electron microscopies. A method of micromanipulation has been developed to ensure that exactly the same objects were studied by both methods. We have shown...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0832464100
更新日期:2003-06-24 00:00:00
abstract::Pancreatic and gastrointestinal D cells were examined by immunocytochemistry using antisera against somatostatin-28 (SS28) and its NH2-terminal fragment SS28-(1-12), followed by the staphylococcal protein A-gold (pAg) complex. In pancreatic and gastric D cells incubated with antiserum against SS28-(1-12) the gold part...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.80.1.215
更新日期:1983-01-01 00:00:00
abstract::Using a HeLa cell line stably transfected with the tat gene from human immunodeficiency virus type 1, we have found that the expression of the regulatory Tat protein suppresses the expression of cellular Mn-containing superoxide dismutase (Mn-SOD). This enzyme is one of the cell's primary defenses against oxygen-deriv...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.90.16.7632
更新日期:1993-08-15 00:00:00
abstract::Escherichia coli DnaJ functions as a typical molecular chaperone in coordination with other heat shock proteins such as DnaK and GrpE in a variety of cellular processes. In this study, it was found that E. coli possesses an analogue of DnaJ, as judged from not only its primary structure but also its possible function....
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.91.3.1054
更新日期:1994-02-01 00:00:00
abstract::Colloidal and sol-gel procedures have been used to prepare heterogeneous catalysts consisting of platinum metal particles with narrow size distributions and well defined shapes dispersed on high-surface-area silica supports. The overall procedure was developed in three stages. First, tetrahedral and cubic colloidal me...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0805691105
更新日期:2008-10-07 00:00:00
abstract::The mitochondrial enzyme glutaminase C (GAC) catalyzes the hydrolysis of glutamine to glutamate plus ammonia, a key step in the metabolism of glutamine by cancer cells. Recently, we discovered a class of allosteric inhibitors of GAC that inhibit cancer cell growth without affecting their normal cellular counterparts, ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1414056112
更新日期:2015-01-13 00:00:00
abstract::Many marine bacteria have evolved to grow optimally at either high (copiotrophic) or low (oligotrophic) nutrient concentrations, enabling different species to colonize distinct trophic habitats in the oceans. Here, we compare the genome sequences of two bacteria, Photobacterium angustum S14 and Sphingopyxis alaskensis...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0903507106
更新日期:2009-09-15 00:00:00
abstract::A comparison was made of the competence for neoplastic transformation in three different sublines of NIH 3T3 cells and multiple clonal derivatives of each. Over 90% of the neoplastic foci produced by an uncloned transformed (t-SA') subline on a confluent background of nontransformed cells were of the dense, multilayer...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.96.5.2093
更新日期:1999-03-02 00:00:00
abstract::Escherichia coli phage N4 transcription is resistant to rifampicin, an inhibitor of the host RNA polymerase, even when the drug is added prior to infection. A rifampicin-resistant RNA polymerase has been detected in disrupted N4 virions. This enzyme shows a requirement for the four ribonucleoside 5'-triphosphates and ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.74.2.520
更新日期:1977-02-01 00:00:00
abstract::The Mars Organic Analyzer (MOA), a microfabricated capillary electrophoresis (CE) instrument for sensitive amino acid biomarker analysis, has been developed and evaluated. The microdevice consists of a four-wafer sandwich combining glass CE separation channels, microfabricated pneumatic membrane valves and pumps, and ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0406798102
更新日期:2005-01-25 00:00:00
abstract::Here we report the development of an in vivo system to study the interaction of stem cells with drugs using a tumor model in the adult Drosophila intestine. Strikingly, we find that some Food and Drug Administration-approved chemotherapeutics that can inhibit the growth of Drosophila tumor stem cells can paradoxically...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1401160111
更新日期:2014-03-25 00:00:00
abstract::The crystal structure of the dodecanucleotide d(CGCAAGCTGGCG) has been determined to a resolution of 2.5 A and refined to an R factor of 19.3% for 1710 reflections. The sequence crystallizes as a B-type double helix, with two G(anti).A(syn) base pairs. These are stabilized by three-center hydrogen bonds to pyrimidines...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.87.17.6693
更新日期:1990-09-01 00:00:00
abstract::The peroxidase-catalyzed aerobic oxidation of a linear aldehyde, leading to the next lower homologue in the triplet state, is accompanied by Norrish type II product ethylene when the substrate is pentanal. This system appears to provide an example of "photobiochemistry without light" because ethylene is a plant hormon...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.91.1.410
更新日期:1994-01-04 00:00:00
abstract::The Get3 ATPase directs the delivery of tail-anchored (TA) proteins to the endoplasmic reticulum (ER). TA-proteins are characterized by having a single transmembrane helix (TM) at their extreme C terminus and include many essential proteins, such as SNAREs, apoptosis factors, and protein translocation components. Thes...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0907522106
更新日期:2009-09-01 00:00:00