Biosynthesis of the enediyne antitumor antibiotic C-1027 involves a new branching point in chorismate metabolism.

abstract：:Negative cooperativity has been observed in CTP synthetase, an allosteric enzyme which contains a regulatory site. Thus, the same enzyme exhibits negative cooperativity for GTP (an effector) and glutamine (a substrate) and positive cooperativity for ATP and UTP (both substrates). In the process of the delineation of t...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Levitzki A,Koshland DE Jr

更新日期：1969-04-01 00:00:00

abstract：:Peptidoglycan (PGN) recognition proteins (PGRPs) are pattern-recognition receptors of the innate immune system that bind and, in some cases, hydrolyze bacterial PGNs. We determined the crystal structure, at 2.30-A resolution, of the C-terminal PGN-binding domain of human PGRP-Ialpha in complex with a muramyl tripeptid...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Guan R,Roychowdhury A,Ember B,Kumar S,Boons GJ,Mariuzza RA

更新日期：2004-12-07 00:00:00

abstract：:We present a theory, and its computer implementation, of how mental simulations underlie the abductions of informal algorithms and deductions from these algorithms. Three experiments tested the theory's predictions, using an environment of a single railway track and a siding. This environment is akin to a universal Tu...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Khemlani SS,Mackiewicz R,Bucciarelli M,Johnson-Laird PN

更新日期：2013-10-15 00:00:00

abstract：:We have used a microfluidic mass sensor to measure the density of single living cells. By weighing each cell in two fluids of different densities, our technique measures the single-cell mass, volume, and density of approximately 500 cells per hour with a density precision of 0.001 g mL(-1). We observe that the intrins...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Grover WH,Bryan AK,Diez-Silva M,Suresh S,Higgins JM,Manalis SR

更新日期：2011-07-05 00:00:00

abstract：:The global configuration of individual, surface-adsorbed molecules of the giant muscle protein titin, labeled with rhodamine conjugates, was followed with confocal microscopy. Fluorescence-emission intensity was reduced because of self-quenching caused by the close spacing between rhodamine dye molecules that formed d...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Grama L,Somogyi B,Kellermayer MS

更新日期：2001-12-04 00:00:00

abstract：:Striatal inhibition plays an important role in models of cortex-basal ganglia function and is altered in many basal ganglia diseases. The gamma-aminobutyric acid ergic spiny projection neuron comprises >95% of striatal neurons, but despite strong anatomical evidence, the electrophysiological properties and functions o...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Czubayko U,Plenz D

更新日期：2002-11-26 00:00:00

abstract：:A cyclophilin (CyP) purified to homogeneity from the polycentric anaerobic rumen fungus Orpinomyces sp. strain PC-2 had a molecular mass of 20.5 kDa and a pI of 8.1. The protein catalyzed the isomerization of the prolyl peptide bond of N-succinyl-Ala-Ala-(cis,trans)-Pro-Phe p-nitroanilide with a kcat/Km value of 9.3 x...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Chen H,Li XL,Ljungdahl LG

更新日期：1995-03-28 00:00:00

abstract：:The attachment of chondrocytes to collagen substrates is stimulated by serum but not by fibronectin. The active material in serum was partially purified and was shown to be a protein by its sensitivity to trypsin and heat and its chromatographic properties. This factor, which we have named chondronectin, is distinct f...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Hewitt AT,Kleinman HK,Pennypacker JP,Martin GR

更新日期：1980-01-01 00:00:00

abstract：:Most Escherichia coli promoters initiate transcription with a purine 7 or 8 nt downstream from the -10 hexamer, but some promoters, including the ribosomal RNA promoter rrnB P1, start 9 nt from the -10 element. We identified promoter and RNA polymerase determinants of this noncanonical rrnB P1 start site using biochem...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Winkelman JT,Chandrangsu P,Ross W,Gourse RL

更新日期：2016-03-29 00:00:00

abstract：:Two anti-tumor monoclonal antibodies, L6 (anticarcinoma) and 1F5 (anti-B lymphoma), were covalently linked to alkaline phosphatase (AP), forming conjugates that could bind to the surface of antigen-positive tumor cells. The conjugates were capable of converting a relatively noncytotoxic prodrug, etoposide phosphate (E...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Senter PD,Saulnier MG,Schreiber GJ,Hirschberg DL,Brown JP,Hellström I,Hellström KE

更新日期：1988-07-01 00:00:00

abstract：:Physical forces have a profound effect on growth, morphology, locomotion, and survival of organisms. At the level of individual cells, the role of mechanical forces is well recognized in eukaryotic physiology, but much less is known about prokaryotic organisms. Recent findings suggest an effect of physical forces on b...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Genova LA,Roberts MF,Wong YC,Harper CE,Santiago AG,Fu B,Srivastava A,Jung W,Wang LM,Krzemiński Ł,Mao X,Sun X,Hui CY,Chen P,Hernandez CJ

更新日期：2019-12-17 00:00:00

abstract：:Fluorescence in situ hybridization (FISH) resolution has advanced because newer techniques use increasingly decondensed chromatin. FISH cannot analyze restriction enzyme cutting sites due to limitations of the hybridization and detection technologies. The RecA-assisted restriction endonuclease (RARE) technique cleaves...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Wang YK,Huff EJ,Schwartz DC

更新日期：1995-01-03 00:00:00

abstract：:L-type Ca(2+) channels play a critical role in regulating Ca(2+)-dependent signaling in cardiac myocytes, including excitation-contraction coupling; however, the subcellular localization of cardiac L-type Ca(2+) channels and their regulation are incompletely understood. Caveolae are specialized microdomains of the pla...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Balijepalli RC,Foell JD,Hall DD,Hell JW,Kamp TJ

更新日期：2006-05-09 00:00:00

abstract：:Failure of embryo implantation accounts for a significant percentage of female infertility. Exquisitely coordinated molecular programs govern the interaction between the competent blastocyst and the receptive uterus. Decidualization, the rapid proliferation and differentiation of endometrial stromal cells into decidua...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Haller M,Yin Y,Ma L

更新日期：2019-09-24 00:00:00

abstract：:Cyclic AMP (cAMP) and calcium are ubiquitous, interdependent second messengers that regulate a wide range of cellular processes. During development of neuronal networks they are critical for the first step of circuit formation, transducing signals required for axon pathfinding. Surprisingly, the spatial and temporal c...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Nicol X,Hong KP,Spitzer NC

更新日期：2011-08-16 00:00:00

abstract：:The TATA box-binding activity of transcription factor IID (TFIID) is autoinhibited by the N-terminal domain of the Drosophila TATA box-binding protein- (TBP) associated factor 230/yeast TBP-associated factor 145 subunit, which binds to the TATA box-binding domain of TBP by mimicking the TATA box structure. Here, we pr...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Kotani T,Banno K,Ikura M,Hinnebusch AG,Nakatani Y,Kawaichi M,Kokubo T

更新日期：2000-06-20 00:00:00

abstract：:The mechanism of contrast enhancement of tumors using magnetic resonance imaging was investigated in MCF7 human breast cancer implanted in nude mice. Dynamic contrast-enhanced images recorded at high spatial resolution were analyzed by an image analysis method based on a physiological model, which included the blood c...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Furman-Haran E,Margalit R,Grobgeld D,Degani H

更新日期：1996-06-25 00:00:00

abstract：:To investigate the evolution of the mammalian sex chromosomes, we have compared the gene content of the X chromosomes in the mammalian groups most distantly related to man (marsupials and monotremes). Previous work established that genes on the long arm of the human X chromosome are conserved on the X chromosomes in a...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Watson JM,Spencer JA,Riggs AD,Graves JA

更新日期：1991-12-15 00:00:00

abstract：:Intracellular transport is interspersed with frequent reversals in direction due to the presence of opposing kinesin and dynein motors on organelles that are carried as cargo. The cause and the mechanism of reversals are unknown, but are a key to understanding how cargos are delivered in a regulated manner to specific...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Soppina V,Rai AK,Ramaiya AJ,Barak P,Mallik R

更新日期：2009-11-17 00:00:00

abstract：:The motor protein cytoplasmic dynein is responsible for most of the minus-end-directed microtubule traffic within cells. Dynein contains four evolutionarily conserved AAA (ATPase associated with various cellular activities) domains that are thought to bind nucleotide; the role of nucleotide binding and hydrolysis in e...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Reck-Peterson SL,Vale RD

更新日期：2004-02-10 00:00:00

abstract：:Seed germination is regulated by endogenous hormonal cues and external environmental stimuli such as water, low temperature, and light. After germination, the young seedling must rapidly establish its root system and the photoautotrophic capability appropriate to its surrounding environment. Light and the phytohormone...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Chen H,Zhang J,Neff MM,Hong SW,Zhang H,Deng XW,Xiong L

更新日期：2008-03-18 00:00:00

abstract：:We used event-related functional MRI to investigate the neural bases of two categories of mental processes believed to contribute to performance of an alphabetization working memory task: memory storage and memory manipulation. Our delayed-response tasks required memory for the identity and position-in-the-display of ...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Postle BR,Berger JS,D'Esposito M

更新日期：1999-10-26 00:00:00

abstract：:The Tat protein coded by human immunodeficiency virus (HIV) is a strong activator of viral gene expression from the long terminal repeat (LTR). It appears that Tat-mediated trans-activation of the HIV LTR is predominantly a transcriptional event. It has been reported that Tat acts at the level of both transcriptional ...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Kamine J,Subramanian T,Chinnadurai G

更新日期：1991-10-01 00:00:00

abstract：:Brain areas' functional repertoires are shaped by their incoming and outgoing structural connections. In empirically measured networks, most connections are short, reflecting spatial and energetic constraints. Nonetheless, a small number of connections span long distances, consistent with the notion that the functiona...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Betzel RF,Bassett DS

更新日期：2018-05-22 00:00:00

abstract：:Various proteins with different biological activities have been observed to be translocated from the nucleus to the cytoplasm in an energy- and signal-dependent manner in eukaryotic cells. This nuclear export is directed by nuclear export signals (NESs), typically characterized by hydrophobic, primarily leucine, amino...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Elfgang C,Rosorius O,Hofer L,Jaksche H,Hauber J,Bevec D

更新日期：1999-05-25 00:00:00

abstract：:Individual diastereomeric phosphoramidites and mixtures of diastereomeric phosphoramidites were evaluated in the iridium-catalyzed amination of allylic carbonates. The original process was conducted with a phosphoramidite ligand containing a resolved 2,2-dihydroxy-1,1-binaphthyl (BINOL) group and a diastereomerically ...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Leitner A,Shu C,Hartwig JF

更新日期：2004-04-20 00:00:00

abstract：:Although it is known that the human genome contains hundreds of microRNA (miRNA) genes and that each miRNA can regulate a large number of mRNA targets, the overall effect of miRNAs on mRNA tissue profiles has not been systematically elucidated. Here, we show that predicted human mRNA targets of several highly tissue-s...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Sood P,Krek A,Zavolan M,Macino G,Rajewsky N

更新日期：2006-02-21 00:00:00

abstract：:We present data that demonstrate that three MR elements isolated from wild populations of Drosophila melanogaster on two continents can cause large deletions of the X chromosome in males. The deleted chromosomes, termed mini-X chromosomes, are induced at a frequency of approximately 1:4000 in chromosomes that are init...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Green MM,Yamamoto MT,Miklos GL

更新日期：1987-07-01 00:00:00

abstract：:A pure population of mast cells was obtained after 14 days of culturing mouse bone marrow cells in the presence of medium derived from concanavalin A-stimulated mouse spleen cells. The cells were characterized as mast cells by their morphologic appearance and histologic staining, by their histamine content (450 ng per...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Razin E,Cordon-Cardo C,Good RA

更新日期：1981-04-01 00:00:00

abstract：:Given their relatively small area, mangroves and their organic sediments are of disproportionate importance to global carbon sequestration and carbon storage. Peat deposition and preservation allows some mangroves to accrete vertically and keep pace with sea-level rise by growing on their own root remains. In this stu...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Ezcurra P,Ezcurra E,Garcillán PP,Costa MT,Aburto-Oropeza O

更新日期：2016-04-19 00:00:00