The catalytic cycle of beta -lactam synthetase observed by x-ray crystallographic snapshots.

abstract：:We determined the frequency of integrated viral DNA in the livers of three woodchucks chronically infected with the woodchuck hepatitis virus before and during 30 weeks of therapy with the nucleoside analog L-FMAU [1-(2-fluoro-5-methyl-beta, L-arabinofuranosyl)uracil, clevudine]. We found that although viral covalentl...

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

authors： Summers J,Mason WS

更新日期：2004-01-13 00:00:00

abstract：:Although Wingless (Wg)/Wnt signaling has been implicated in heart development of multiple organisms, conflicting results have been reported regarding the role of Wnt/beta-catenin pathway in cardiac myogenesis: Wg/armadillo signaling promotes heart development in Drosophila, whereas activation of Wnt/beta-catenin signa...

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

authors： Naito AT,Shiojima I,Akazawa H,Hidaka K,Morisaki T,Kikuchi A,Komuro I

更新日期：2006-12-26 00:00:00

abstract：:Climate change is increasing fire activity in the western United States, which has the potential to accelerate climate-induced shifts in vegetation communities. Wildfire can catalyze vegetation change by killing adult trees that could otherwise persist in climate conditions no longer suitable for seedling establishmen...

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

authors： Davis KT,Dobrowski SZ,Higuera PE,Holden ZA,Veblen TT,Rother MT,Parks SA,Sala A,Maneta MP

更新日期：2019-03-26 00:00:00

abstract：:Operant conditioning techniques were used to assess how gender and song familiarity affect song discrimination in adult zebra finches (Taeniopygia guttata). Twenty-five males and females, divided into five cohorts, were trained to discriminate between conspecific songs at different times of year. Males discriminating ...

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

authors： Cynx J,Nottebohm F

更新日期：1992-02-15 00:00:00

abstract：:Synthetic bradykinin, a nonapeptide formed from alpha-2 globulin in plasma, injected intra-arterially or intraperitoneally in cats in doses of 10-50 mug, evoked activity in the central nervous system in pathways associated with the signaling of pain. Similar injections of bradykinin in intact normal cats and dogs evok...

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

authors： Lim RK,Krauthamer G,Guzman F,Fulp RR

更新日期：1969-07-01 00:00:00

abstract：:Aminoacyl-tRNA synthetases (amino acid-tRNA ligases, EC 6.1.1.-) catalyze the aminoacylation of specific amino acids onto their cognate tRNAs with extraordinary accuracy. Recent reports, however, indicate that this class of enzymes may play other roles in cellular metabolism. Several aminoacyl-tRNA synthetases are her...

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

authors： Rapaport E,Remy P,Kleinkauf H,Vater J,Zamecnik PC

更新日期：1987-11-01 00:00:00

abstract：:The redox siblings nitroxyl (HNO) and nitric oxide (NO) have often been assumed to undergo casual redox reactions in biological systems. However, several recent studies have demonstrated distinct pharmacological effects for donors of these two species. Here, infusion of the HNO donor Angeli's salt into normal dogs res...

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

authors： Miranda KM,Paolocci N,Katori T,Thomas DD,Ford E,Bartberger MD,Espey MG,Kass DA,Feelisch M,Fukuto JM,Wink DA

更新日期：2003-08-05 00:00:00

abstract：:Mechanical stability in many biological materials is provided by the crosslinking of large structural proteins with gamma-glutamyl-epsilon-lysyl amide bonds. The three-dimensional structure of human recombinant factor XIII (EC 2.3.2.13 zymogen; protein-glutamine:amine gamma-glutamyltransferase a chain), a transglutami...

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

authors： Yee VC,Pedersen LC,Le Trong I,Bishop PD,Stenkamp RE,Teller DC

更新日期：1994-07-19 00:00:00

abstract：:Whereas target-specific drugs are available for treating ERBB2-overexpressing and hormone receptor-positive breast cancers, no tailored therapy exists for hormone receptor- and ERBB2-negative ("triple-negative") mammary carcinomas. Triple-negative tumors account for 15% of all breast cancers and frequently harbor defe...

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

authors： Rottenberg S,Jaspers JE,Kersbergen A,van der Burg E,Nygren AO,Zander SA,Derksen PW,de Bruin M,Zevenhoven J,Lau A,Boulter R,Cranston A,O'Connor MJ,Martin NM,Borst P,Jonkers J

更新日期：2008-11-04 00:00:00

abstract：:Seismic magnitudes determined from surface and body waves for the Soviet underground nuclear explosion of September 14, 1988, are used to calculate the yield of that event from previously derived calibration curves. The yield obtained by combining the two seismic estimates is 113 kilotons, which is very close to those...

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

authors： Sykes LR,Ekström G

更新日期：1989-05-01 00:00:00

abstract：:Effective therapies for most solid cancers, especially those that have progressed to metastasis, remain elusive because of inherent and acquired resistance of tumor cells to conventional treatments. Additionally, the effective therapeutic window for many protocols can be very narrow, frequently resulting in toxicity. ...

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

authors： Lebedeva IV,Washington I,Sarkar D,Clark JA,Fine RL,Dent P,Curiel DT,Turro NJ,Fisher PB

更新日期：2007-02-27 00:00:00

abstract：:Developmentally regulated genes in Drosophila, which are conserved through evolution, are potential candidates for key functions in biological processes such as cell cycle, programmed cell death, and cancer. We report cloning and characterization of the human homologue of the Drosophila seven in absentia gene (HUMSIAH...

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

authors： Nemani M,Linares-Cruz G,Bruzzoni-Giovanelli H,Roperch JP,Tuynder M,Bougueleret L,Cherif D,Medhioub M,Pasturaud P,Alvaro V,der Sarkissan H,Cazes L,Le Paslier D,Le Gall I,Israeli D,Dausset J,Sigaux F,Chumakov I,Oren M,

更新日期：1996-08-20 00:00:00

abstract：:Preparations of the hemin-controlled repressor (HCR) from rabbit reticulocytes contain 3':5'-cyclic-AMP-independent protein kinase activity for the smallest subunit of the peptide initiation factor eIF-2 and for proteins of reticulocyte 40S ribosomal subunits. Binding of the ternary complex formed between Met-tRNAf, G...

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

authors： Kramer G,Henderson AB,Pinphanichakarn P,Wallis MH,Hardesty B

更新日期：1977-04-01 00:00:00

abstract：:Addition of Na+ to Na+-depleted Swiss 3T3 cells causes a rapid and dramatic increase in intracellular pH, as monitored by uptake of the weak acid 5,5-dimethyloxazolidine-2,4-dione. The effect of Na+ is concentration dependent (half-maximal effect at 38 mM); this cation can be replaced by Li+ but not by K+ or the choli...

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

authors： Schuldiner S,Rozengurt E

更新日期：1982-12-01 00:00:00

abstract：:Production of reactive oxygen intermediates (ROI) and a form of programmed cell death called hypersensitive response (HR) are often associated with disease resistance of plants. We have previously shown that the Rac homolog of rice, OsRac1, is a regulator of ROI production and cell death in rice. Here we show that the...

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

authors： Ono E,Wong HL,Kawasaki T,Hasegawa M,Kodama O,Shimamoto K

更新日期：2001-01-16 00:00:00

abstract：:Environmental cues modulate a variety of intracellular pathways whose signaling is integrated by the molecular mechanism that constitutes the circadian clock. Although the essential gears of the circadian machinery have been elucidated, very little is known about the signaling systems regulating it. Here, we report th...

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

authors： Yujnovsky I,Hirayama J,Doi M,Borrelli E,Sassone-Corsi P

更新日期：2006-04-18 00:00:00

abstract：:Aromatic polyketides make up a large class of natural products with diverse bioactivity. During biosynthesis, linear poly-β-ketone intermediates are regiospecifically cyclized, yielding molecules with defined cyclization patterns that are crucial for polyketide bioactivity. The aromatase/cyclases (ARO/CYCs) are respon...

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

authors： Caldara-Festin G,Jackson DR,Barajas JF,Valentic TR,Patel AB,Aguilar S,Nguyen M,Vo M,Khanna A,Sasaki E,Liu HW,Tsai SC

更新日期：2015-12-15 00:00:00

abstract：:A genetic analysis is necessary to gain a greater understanding of the complex developmental processes in mammals. Toward this end, an insertional transgenic mouse mutant has been isolated that results in abnormal germ-cell development. This recessive mutation manifests as infertility in both males and females and is ...

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

authors： Pellas TC,Ramachandran B,Duncan M,Pan SS,Marone M,Chada K

更新日期：1991-10-01 00:00:00

abstract：:Two objects with homologous landmarks are said to be of the same shape if the configuration of landmarks of one object can be exactly matched with that of the other by translation, rotation/reflection, and scaling. In an earlier paper, the authors proposed statistical analysis of shape by considering logarithmic diffe...

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

authors： Rao CR,Suryawanshi S

更新日期：1998-04-14 00:00:00

abstract：:The first step in the replication of the adenovirus genome is the covalent attachment of the 5'-terminal nucleotide, dCMP, to the virus-encoded terminal protein precursor (pTP). This reaction can be observed in vitro and has been previously shown to be dependent upon either viral DNA or linearized plasmid DNA containi...

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

authors： Challberg MD,Rawlins DR

更新日期：1984-01-01 00:00:00

abstract：:Outdoor ozone transported indoors initiates oxidative chemistry, forming volatile organic products. The influence of ozone chemistry on indoor air composition has not been directly quantified in normally occupied residences. Here, we explore indoor ozone chemistry in a house in California with two adult inhabitants. W...

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

authors： Liu Y,Misztal PK,Arata C,Weschler CJ,Nazaroff WW,Goldstein AH

更新日期：2021-02-09 00:00:00

abstract：:We have constructed yeast strains that secrete functional mouse-human chimeric antibody and its Fab fragment into the culture medium. For chimeric whole antibody, cDNA copies of the chimeric light-chain and heavy-chain genes of an anti-tumor antibody were inserted into vectors containing the yeast phosphoglycerate kin...

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

authors： Horwitz AH,Chang CP,Better M,Hellstrom KE,Robinson RR

更新日期：1988-11-01 00:00:00

abstract：:RsbR is a regulator of sigma(B), the RNA polymerase sigma factor subunit responsible for transcribing the general stress response genes when environmental stress is imposed on Bacillus subtilis. The C-terminal domain of RsbR and its paralogues is a substrate for the kinase function of another sigma(B) regulator, RsbT,...

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

authors： Murray JW,Delumeau O,Lewis RJ

更新日期：2005-11-29 00:00:00

abstract：:Topical application of phorbol myristate acetate (PMA) elicits intense local inflammation that facilitates outgrowth of premalignant lesions in skin after carcinogen exposure. The inflammatory response to PMA treatment activates immune stimulatory mechanisms. However, we show here that PMA exposure also induces plasma...

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

authors： Muller AJ,Sharma MD,Chandler PR,Duhadaway JB,Everhart ME,Johnson BA 3rd,Kahler DJ,Pihkala J,Soler AP,Munn DH,Prendergast GC,Mellor AL

更新日期：2008-11-04 00:00:00

abstract：:The O(2) reduction site of cytochrome c oxidase (CcO), comprising iron (Fe(a3)) and copper (Cu(B)) ions, is probed by x-ray structural analyses of CO, NO, and CN(-) derivatives to investigate the mechanism of the complete reduction of O(2). Formation of the derivative contributes to the trigonal planar coordination of...

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

authors： Muramoto K,Ohta K,Shinzawa-Itoh K,Kanda K,Taniguchi M,Nabekura H,Yamashita E,Tsukihara T,Yoshikawa S

更新日期：2010-04-27 00:00:00

abstract：:Treatment of small resting B cells with soluble F(ab')2 fragments of anti-IgM, an analogue of T-independent type 2 antigens, induced activation characterized by proliferation and the expression of surface CD5. In contrast, B cells induced to proliferate in response to thymus-dependent inductive signals provided by eit...

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

authors： Wortis HH,Teutsch M,Higer M,Zheng J,Parker DC

更新日期：1995-04-11 00:00:00

abstract：:A mammalian A-type cyclin, cyclin A1, is highly expressed in testes of both human and mouse and targeted mutagenesis in the mouse has revealed the unique requirement for cyclin A1 in the progression of male germ cells through the meiotic cell cycle. While very low levels of cyclin A1 have been reported in the human he...

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

authors： Liao C,Wang XY,Wei HQ,Li SQ,Merghoub T,Pandolfi PP,Wolgemuth DJ

更新日期：2001-06-05 00:00:00

abstract：:Previous studies have shown that in mammalian cells proteins of large molecular weight are degraded more rapidly than small ones. Evidence is presented here that half-lives of proteins are also related to their isoelectric points. A double-isotope method was used to compare degradative rates of soluble proteins separa...

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

authors： Dice JF,Goldberg AL

更新日期：1975-10-01 00:00:00

abstract：:Methicillin-resistant Staphylococcus aureus (MRSA) is an emerging cause of catheter-associated urinary tract infection (CAUTI), which frequently progresses to more serious invasive infections. We adapted a mouse model of CAUTI to investigate how catheterization increases an individual's susceptibility to MRSA UTI. Thi...

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

authors： Walker JN,Flores-Mireles AL,Pinkner CL,Schreiber HL 4th,Joens MS,Park AM,Potretzke AM,Bauman TM,Pinkner JS,Fitzpatrick JAJ,Desai A,Caparon MG,Hultgren SJ

更新日期：2017-10-10 00:00:00

abstract：:The mammalian form of the protozoan parasite Leishmania mexicana contains high activity of a cysteine proteinase (LmCPb) encoded on a tandem array of 19 genes (lmcpb). Homozygous null mutants for lmcpb have been produced by targeted gene disruption. All life-cycle stages of the mutant can be cultured in vitro, demonst...

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

authors： Mottram JC,Souza AE,Hutchison JE,Carter R,Frame MJ,Coombs GH

更新日期：1996-06-11 00:00:00