Abstract:
:A cell of the bacterium Escherichia coli was tethered covalently to a glass coverslip by a single flagellum, and its rotation was stopped by using optical tweezers. The tweezers acted directly on the cell body or indirectly, via a trapped polystyrene bead. The torque generated by the flagellar motor was determined by measuring the displacement of the laser beam on a quadrant photodiode. The coverslip was mounted on a computer-controlled piezo-electric stage that moved the tether point in a circle around the center of the trap so that the speed of rotation of the motor could be varied. The motor generated approximately 4500 pN nm of torque at all angles, regardless of whether it was stalled, allowed to rotate very slowly forwards, or driven very slowly backwards. This argues against models of motor function in which rotation is tightly coupled to proton transit and back-transport of protons is severely limited.
journal_name
Proc Natl Acad Sci U S Aauthors
Berry RM,Berg HCdoi
10.1073/pnas.94.26.14433subject
Has Abstractpub_date
1997-12-23 00:00:00pages
14433-7issue
26eissn
0027-8424issn
1091-6490journal_volume
94pub_type
杂志文章abstract::The protein defective in hereditary hemochromatosis, called HFE, is similar to MHC class I-type proteins and associates with beta2-microglobulin (beta2M). Its association with beta2M was previously shown to be necessary for its stability, normal intracellular processing, and cell surface expression in transfected COS ...
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.042701499
更新日期:2002-03-05 00:00:00
abstract::The gene for the RNA-dependent eIF-2 alpha protein kinase (PKR) was isolated from mouse genomic DNA and characterized. The mouse PKR gene contains 16 exons and spans about 28 kilobase pairs. Exon 1 is untranslated; the AUG translation initiation site is located early in the second exon. Exon 16 includes the UAG transl...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
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abstract::The apparent failure of infants to understand "object permanence" by reaching for hidden objects is perhaps the most striking and debated phenomenon in cognitive development. Of particular interest is the extent to which infants perceive and remember objects in a similar way to that of adults. Here we report two findi...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
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doi:10.1073/pnas.0507626102
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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doi:10.1073/pnas.0401952101
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abstract::Cells transformed by Friend virus in liquid suspension culture respond to low concentrations of dimethylsulfoxide by initiating hemoglobin synthesis. The kinetics of appearance of such differentiated erythroid cells is consistent with either the induction of differentiation in a uniformly susceptible population of tra...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
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abstract::Molecular beacons are DNA probes that form a stem-and-loop structure and possess an internally quenched fluorophore. When they bind to complementary nucleic acids, they undergo a conformational transition that switches on their fluorescence. These probes recognize their targets with higher specificity than probes that...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
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abstract::Large changes in solvent accessibility to aspartate transcarbamylase (aspartate carbamoyltransferase, carbamoylphosphate:L-aspartate carbamoyltransferase, EC 2.1.3.2), as monitored by tritium exchange, result from binding of substrates and substrate analogs to the catalytic subunit (c3), binding of nucleoside triphosp...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
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doi:10.1073/pnas.78.11.6759
更新日期:1981-11-01 00:00:00
abstract::Productive T cell recognition of antigen-presenting cells (APCs) is normally accompanied by the formation of a cell-cell contact called the "immunological synapse." Our understanding of the steps leading up to this formation has been limited by the absence of tools for analyzing 3D surfaces and surface distributions a...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
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更新日期:2007-11-06 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
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更新日期:1996-12-10 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
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更新日期:2014-02-11 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
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更新日期:2000-07-05 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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更新日期:2005-07-05 00:00:00
abstract::After prolonged exposure to ascorbate, collagen synthesis in cultured human skin fibroblasts increased approximately 8-fold with no significant change in synthesis of noncollagen protein. This effect of ascorbate appears to be unrelated to its cofactor function in collagen hydroxylation. The collagenous protein secret...
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.78.5.2879
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abstract::Neurons in macaque ventral premotor cortex and inferior parietal lobe discharge during both the observation and the execution of motor acts. It has been claimed that these so-called mirror neurons form the basis of action understanding by matching the visual input with the corresponding motor program (direct matching)...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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更新日期:1997-11-25 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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更新日期:2006-06-27 00:00:00
abstract::Among yeasts that underwent whole-genome duplication (WGD), Kluyveromyces polysporus represents the lineage most distant from Saccharomyces cerevisiae. By sequencing the K. polysporus genome and comparing it with the S. cerevisiae genome using a likelihood model of gene loss, we show that these species diverged very 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.0608218104
更新日期:2007-05-15 00:00:00
abstract::The N,N'-diacetyllactosediamine (lacdiNAc) pathway of complex-type oligosaccharide synthesis is controlled by a UDP-GalNAc:GlcNAc beta-R beta 1-->4-N-acetylgalac-tesaminyltransferase (beta 4-GalNAcT) that acts analogously to the common UDP-Gal:GlcNAc beta-R beta 1-->4-galactosyltransferase (beta 4-GalT). LacdiNAc-base...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
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doi:10.1073/pnas.93.19.10111
更新日期:1996-09-17 00:00:00
abstract::By commandeering cellular translation initiation factors, or destroying those dispensable for viral mRNA translation, viruses often suppress host protein synthesis. In contrast, cellular protein synthesis proceeds in human cytomegalovirus (HCMV)-infected cells, forcing viral and cellular mRNAs to compete for limiting ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
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doi:10.1073/pnas.1202829109
更新日期:2012-04-10 00:00:00
abstract::Across phyla, the ribosomes-the central molecular machines for translation of genetic information-exhibit an overall preserved architecture and a conserved functional core. The natural heterogeneity of the ribosome periodically phases a debate on their functional specialization and the tissue-specific variations of th...
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.1912060116
更新日期:2019-11-05 00:00:00
abstract::Initiation of bovine papillomavirus (BPV) DNA synthesis in vivo and in vitro depends on the interaction of the viral initiator protein E1 with the replication origin (ori+ DNA). The viral E2 protein assists this interaction, resulting in a cooperative assembly of both proteins on the replication origin. Using gel mobi...
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.91.19.8895
更新日期:1994-09-13 00:00:00
abstract::As an electron transfer-driven proton pump, cytochrome c oxidase (ferrocytochrome-c:oxygen oxidoreductase, EC 1.9.3.1) must alternate between two conformations in each valence state of the redox element associated with ion translocation. Using second derivative absorption spectroscopy, the conformation of the cytochro...
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.88.16.7281
更新日期:1991-08-15 00:00:00
abstract::Myosins play countless critical roles in the cell, each requiring it to be activated at a specific location and time. To control myosin VI with this specificity, we created an optogenetic tool for activating myosin VI by fusing the light-sensitive Avena sativa phototropin1 LOV2 domain to a peptide from Dab2 (LOVDab), ...
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.1614716114
更新日期:2017-02-28 00:00:00
abstract::Natural killer (NK) cells play a critical role in controlling malignancies. Susceptibility or resistance to lung cancer, for example, specifically depends on NK cell function. Nevertheless, intrinsic factors that control NK cell-mediated clearance of lung cancer are unknown. Here we report that NK cells exposed to exo...
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.1804931115
更新日期:2018-11-13 00:00:00
abstract::The bacterial actin homolog, MreB, forms helical cables within the cell that are required for maintenance of a rod shape. These helical structures are thought to be involved in the spatial organization of cell wall (peptidoglycan) synthesizing complexes of penicillin-binding proteins (PBPs). Here, we examined the role...
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.0507937102
更新日期:2005-12-20 00:00:00