36 results match your criteria catalytic p68

Overexpression of oncogenic H-Ras in hTERT-immortalized and SV40-transformed human cells targets replicative and specialized DNA polymerases for depletion.

PLoS One 2021 7;16(5):e0251188. Epub 2021 May 7.

Department of Pathology, The Jake Gittlen Laboratories for Cancer Research, Penn State University College of Medicine, Hershey, Pennsylvania, United States of America.

DNA polymerases play essential functions in replication fork progression and genome maintenance. DNA lesions and drug-induced replication stress result in up-regulation and re-localization of specialized DNA polymerases η and κ. Although oncogene activation significantly alters DNA replication dynamics, causing replication stress and genome instability, little is known about DNA polymerase expression and regulation in response to oncogene activation. Read More

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Identification of PCNA-interacting protein motifs in human DNA polymerase δ.

Biosci Rep 2020 04;40(4)

Laboratory of Genomic Instability and Diseases, Department of Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar 751023, India.

DNA polymerase δ (Polδ) is a highly processive essential replicative DNA polymerase. In humans, the Polδ holoenzyme consists of p125, p50, p68 and p12 subunits and recently, we showed that the p12 subunit exists as a dimer. Extensive biochemical studies suggest that all the subunits of Polδ interact with the processivity factor proliferating cell nuclear antigen (PCNA) to carry out a pivotal role in genomic DNA replication. Read More

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The p12 subunit of human polymerase δ uses an atypical PIP box for molecular recognition of proliferating cell nuclear antigen (PCNA).

J Biol Chem 2019 03 17;294(11):3947-3956. Epub 2019 Jan 17.

the Structural Biology Laboratory, Elettra-Sincrotrone Trieste S.C.p.A., Trieste 34149, Italy,

Human DNA polymerase δ is essential for DNA replication and acts in conjunction with the processivity factor proliferating cell nuclear antigen (PCNA). In addition to its catalytic subunit (p125), pol δ comprises three regulatory subunits (p50, p68, and p12). PCNA interacts with all of these subunits, but only the interaction with p68 has been structurally characterized. Read More

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Topoisomerase 3β interacts with RNAi machinery to promote heterochromatin formation and transcriptional silencing in Drosophila.

Nat Commun 2018 11 23;9(1):4946. Epub 2018 Nov 23.

Lab of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, MD, 21224, USA.

Topoisomerases solve topological problems during DNA metabolism, but whether they participate in RNA metabolism remains unclear. Top3β represents a family of topoisomerases carrying activities for both DNA and RNA. Here we show that in Drosophila, Top3β interacts biochemically and genetically with the RNAi-induced silencing complex (RISC) containing AGO2, p68 RNA helicase, and FMRP. Read More

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November 2018

Multiple Forms of Human DNA Polymerase Delta Sub-Assembling in Cellular DNA Transactions.

Curr Protein Pept Sci 2016 ;17(8):746-755

Jiangsu University Institute of Life Sciences, China.

Among three major replicative DNA polymerases of the B-family, Pol α, Pol δ and Pol ε, Pol δ plays an essential role in chromosomal DNA replication and is also involved in various DNA repair processes in eukaryotes. Human Pol δ is commonly viewed as a heterotetrameric complex, consisting of the catalytic subunit p125 and second subunit p50, together with two additional accessory subunits, p68 and p12. A growing body of research has shown that the latter subunits play a critical role in the regulation of Pol δ functions. Read More

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February 2017

An in silico approach to elucidate structure based functional evolution of oxacillinase.

Comput Biol Chem 2016 10 8;64:145-153. Epub 2016 Jun 8.

Department of Biochemistry and Medical Biotechnology, Calcutta School of Tropical Medicine, 108 C.R. Avenue, Kolkata 700073, India. Electronic address:

Bacterial Oxacillinases (OXAs), genetically being extremely diverse and highly versatile in hydrolyzing antibiotics of different classes, holds utmost significant clinical importance. Hence, to analyze functional evolution of this enzyme, plausible changes in drug profile, affinity and binding stability of different subclasses of OXA with their preferred drugs, viz. penicillin, ceftazidime, imipenem/meropenem were investigated. Read More

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October 2016

DNA-Directed Polymerase Subunits Play a Vital Role in Human Telomeric Overhang Processing.

Mol Cancer Res 2015 Mar 17;13(3):402-10. Epub 2014 Dec 17.

Department of Biological Sciences, Hunter College and CUNY Graduate Center, New York, New York.

Unlabelled: Telomeres consist of TTAGGG repeats bound by the shelterin complex and end with a 3' overhang. In humans, telomeres shorten at each cell division, unless telomerase (TERT) is expressed and able to add telomeric repeats. For effective telomere maintenance, the DNA strand complementary to that made by telomerase must be synthesized. Read More

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Characterization of human DNA polymerase delta and its subassemblies reconstituted by expression in the MultiBac system.

PLoS One 2012 18;7(6):e39156. Epub 2012 Jun 18.

Institute of Life Sciences, Jiangsu University, Zhenjiang, Jiangsu, People's Republic of China.

Mammalian DNA polymerase δ (Pol δ), a four-subunit enzyme, plays a crucial and versatile role in DNA replication and DNA repair processes. We have reconstituted human Pol δ complexes in insect cells infected with a single baculovirus into which one or more subunits were assembled. This system allowed for the efficient expression of the tetrameric Pol δ holoenzyme, the p125/p50 core dimer, the core+p68 trimer and the core+p12 trimer, as well as the p125 catalytic subunit. Read More

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December 2012

DNA damage alters DNA polymerase delta to a form that exhibits increased discrimination against modified template bases and mismatched primers.

Nucleic Acids Res 2009 Feb 11;37(2):647-57. Epub 2008 Dec 11.

Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, NY 10595, USA.

Human DNA polymerase delta (Pol delta4), a key enzyme in chromosomal replication, is a heterotetramer composed of the p125, p50, p68 and p12 subunits. Genotoxic agents such as UV and alkylating chemicals trigger a DNA damage response in which Pol delta4 is converted to a trimer (Pol delta3) by degradation of p12. We show that Pol delta3 has altered enzymatic properties: it is less able to perform translesion synthesis on templates containing base lesions (O(6)-MeG, 8-oxoG, an abasic site or a thymine-thymine dimer); a greater proofreading activity; an increased exonuclease/polymerase activity ratio; a decreased tendency for the insertion of wrong nucleotides, and for the extension of mismatched primers. Read More

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February 2009

Protein phosphatase-1 is targeted to DNA polymerase delta via an interaction with the p68 subunit.

Biochemistry 2008 Oct 1;47(43):11367-76. Epub 2008 Oct 1.

Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, New York 10595, USA.

Protein phosphatase-1 (PP1) is a Ser/Thr protein phosphatase that participates in the phosphorylation/dephosphorylation regulation of a diverse range of cellular processes. The PP1 catalytic subunit (PP1) achieves this by its ability to interact with many targeting subunits such that PP1 activity is thereby specified against phosphoprotein substrates in the microvicinity of its targeting subunit. DNA polymerase delta (Pol delta) is a key enzyme in mammalian chromosomal replication. Read More

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October 2008

Genome segment 6 of Antheraea mylitta cypovirus encodes a structural protein with ATPase activity.

Virology 2008 Jul 16;377(1):7-18. Epub 2008 May 16.

Department of Biotechnology, Indian Institute of Technology, Kharagpur, Kharagpur 721302, West Bengal, India.

The genome segment 6 (S6) of the 11 double stranded RNA genomes from Antheraea mylitta cypovirus was converted into cDNA, cloned and sequenced. S6 consisted of 1944 nucleotides with an ORF of 607 amino acids and could encode a protein of 68 kDa, termed P68. Motif scan and molecular docking analysis of P68 showed the presence of two cystathionine beta synthase (CBS) domains and ATP binding sites. Read More

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Four human thiopurine s-methyltransferase alleles severely affect protein structure and dynamics.

J Mol Biol 2008 Jun 18;379(4):803-14. Epub 2008 Apr 18.

Department of Biochemistry, University of Washington, Seattle, WA 98195-5013, USA.

Thiopurine S-methyltransferase (TPMT) metabolizes cytotoxic thiopurine drugs used in the treatment of leukemia and inflammatory bowel disease. TPMT is a major pharmacogenomic target with 23 alleles identified to date. Several of these alleles cause rapid protein degradation and/or aggregation, making it extremely difficult to study the structural impact of the TPMT polymorphisms experimentally. Read More

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Human Mcm10 regulates the catalytic subunit of DNA polymerase-alpha and prevents DNA damage during replication.

Mol Biol Cell 2007 Oct 15;18(10):4085-95. Epub 2007 Aug 15.

Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA.

In Saccharomyces cerevisiae, minichromosome maintenance protein (Mcm) 10 interacts with DNA polymerase (pol)-alpha and functions as a nuclear chaperone for the catalytic subunit, which is rapidly degraded in the absence of Mcm10. We report here that the interaction between Mcm10 and pol-alpha is conserved in human cells. We used a small interfering RNA-based approach to deplete Mcm10 in HeLa cells, and we observed that the catalytic subunit of pol-alpha, p180, was degraded with similar kinetics as Mcm10, whereas the regulatory pol-alpha subunit, p68, remained unaffected. Read More

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October 2007

DEAD-box RNA helicase subunits of the Drosha complex are required for processing of rRNA and a subset of microRNAs.

Nat Cell Biol 2007 May 15;9(5):604-11. Epub 2007 Apr 15.

Institute of Molecular and Cellular Biosciences, University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-0032, Japan.

MicroRNAs (miRNAs) control cell proliferation, differentiation and fate through modulation of gene expression by partially base-pairing with target mRNA sequences. Drosha is an RNase III enzyme that is the catalytic subunit of a large complex that cleaves pri-miRNAs with distinct structures into pre-miRNAs. Here, we show that both the p68 and p72 DEAD-box RNA helicase subunits in the mouse Drosha complex are indispensable for survival in mice, and both are required for primary miRNA and rRNA processing. Read More

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The RNA helicases p68/p72 and the noncoding RNA SRA are coregulators of MyoD and skeletal muscle differentiation.

Dev Cell 2006 Oct;11(4):547-60

Muscle Gene Expression Group, Laboratory of Muscle Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, Maryland 20829, USA.

MyoD regulates skeletal myogenesis. Since proteins associated with MyoD exert regulatory functions, their identification is expected to contribute important insights into the mechanisms governing gene expression in skeletal muscle. We have found that the RNA helicases p68/p72 are MyoD-associated proteins and that the noncoding RNA SRA also immunoprecipitates with MyoD. Read More

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October 2006

Role of the second-largest subunit of DNA polymerase alpha in the interaction between the catalytic subunit and hyperphosphorylated retinoblastoma protein in late S phase.

Biochim Biophys Acta 2006 Sep 25;1764(9):1447-53. Epub 2006 Jul 25.

Department of Biology, Faculty of Science, Tokyo University of Science, RIKADAI, Kagurazaka 1-3, Tokyo 162-8601, Japan.

DNA polymerase alpha (pol-alpha) is a heterotetrameric enzyme (p180-p68-p58-p48 in mouse) that is essential for the initiation of chain elongation during DNA replication. The catalytic (p180) and p68 subunits of pol-alpha are phosphorylated by Cdk-cyclin complexes, with p68 being hyperphosphorylated by cyclin-dependent kinases in G(2) phase of the cell cycle. The activity of Cdk2-cyclin A increases during late S phase and peaks in G(2) phase. Read More

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September 2006

Functional roles of p12, the fourth subunit of human DNA polymerase delta.

J Biol Chem 2006 May 28;281(21):14748-55. Epub 2006 Feb 28.

Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, NY 10595, USA.

Mammalian DNA polymerase delta (pol delta), a key enzyme of chromosomal DNA replication, consists of four subunits as follows: the catalytic subunit; p125, which is tightly associated with the p50 subunit; p68, a proliferating cell nuclear antigen (PCNA)-binding protein; and a fourth subunit, p12. In this study, the functional roles of the p12 subunit of pol delta were studied. The inter-subunit interactions of the p12 subunit were determined by yeast two-hybrid assays and by pulldown assays. Read More

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Reconstitution and characterization of the human DNA polymerase delta four-subunit holoenzyme.

Biochemistry 2002 Nov;41(44):13133-42

Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, New York 10595, USA.

Mammalian DNA polymerase delta was originally characterized as a tightly associated heterodimer consisting of the catalytic subunit, p125, and the p50 subunit. Recently, two additional subunits, the third (p68) and fourth subunits (p12), have been identified. The heterotetrameric human pol delta complex was reconstituted by overexpression of the four subunits in Sf9 cells, followed by purification to near-homogeneity using FPLC chromatography. Read More

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November 2002

Properties, stage-dependent expression and localization of Plasmodium falciparum M1 family zinc-aminopeptidase.

Parasitology 2002 Jul;125(Pt 1):1-10

Laboratoire de Biologie Parasitaire, Protistologie, Helminthologie, Muséum National d'Histoire Naturelle, EA 3335 et FR 63 CNRS, Paris, France.

A Plasmodium falciparum single copy gene predicting a 122 kDa protein belonging to the Ml family of zincmetallopeptidases was previously reported and related to erythrocytic schizont proteins of 96 (p96) and 68 (p68) kDa. By using protease inhibitors during parasite harvest and enzyme preparations, and polyclonal antibodies specific for 2 peptidic domains deduced from the gene, we identified the 120 kDa precursor and demonstrated its processing into p96 and p68. The N-terminal ends of p96 and p68 were mapped between glycine-123 and lysine-163, both proteins thus containing the catalytic domain. Read More

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Rearrangement of structured RNA via branch migration structures catalysed by the highly related DEAD-box proteins p68 and p72.

Nucleic Acids Res 2001 May;29(10):2088-96

Medizinische Biochemie und Molekularbiologie, Universität des Saarlandes, D-66421 Homburg, Germany.

RNA helicases, like their DNA-specific counterparts, can function as processive enzymes, unwinding RNA with a defined step size in a unidirectional fashion. Recombinant nuclear DEAD-box protein p68 and its close relative p72 are reported here to function in a similar fashion, though the processivity of both RNA helicases appears to be limited to only a few consecutive catalytic steps. The two proteins resemble each other also with regard to other biochemical properties. Read More

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E2F regulates growth-dependent transcription of genes encoding both catalytic and regulatory subunits of mouse primase.

Genes Cells 2001 Jan;6(1):57-70

Cellular Physiology Laboratory, RIKEN (The Institute of Physical and Chemical Research), Wako, Saitama 351-0198, Japan.

DNA polymerase alpha-primase is one of the principal enzymes involved in eukaryotic chromosomal DNA replication. Mouse DNA polymerase alpha-primase consists of four subunits with molecular masses of 180, 68, 54 and 46 kDa. Protein and mRNA expression levels of the four subunits are up-regulated in a coordinated manner in response to growth stimulation. Read More

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January 2001

Evidence that DNA polymerase delta isolated by immunoaffinity chromatography exhibits high-molecular weight characteristics and is associated with the KIAA0039 protein and RPA.

Biochemistry 2000 Jun;39(24):7245-54

Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla 10595, USA.

DNA polymerase delta, the key enzyme for eukaryotic chromosomal replication, has been well characterized as consisting of a core enzyme of a 125 kDa catalytic subunit and a smaller 50 kDa subunit. However, less is known about the other proteins that may comprise additional subunits or participate in the macromolecular protein complex that is involved in chromosomal DNA replication. In this study, the properties of calf thymus pol delta preparations isolated by immunoaffinity chromatography were investigated. Read More

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The second-largest subunit of the mouse DNA polymerase alpha-primase complex facilitates both production and nuclear translocation of the catalytic subunit of DNA polymerase alpha.

Mol Cell Biol 1998 Jun;18(6):3552-62

The Institute of Physical and Chemical Research, Wako, Saitama 351-01, Japan.

DNA polymerase alpha-primase is a replication enzyme necessary for DNA replication in all eukaryotes examined so far. Mouse DNA polymerase alpha is made up of four subunits, the largest of which is the catalytic subunit with a molecular mass of 180 kDa (p180). This subunit exists as a tight complex with the second-largest subunit (p68), whose physiological role has remained unclear up until now. Read More

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CD28 signal transduction: tyrosine phosphorylation and receptor association of phosphoinositide-3 kinase correlate with Ca(2+)-independent costimulatory activity.

Eur J Immunol 1994 Nov;24(11):2732-9

Department of Veterans Affairs Medical Center Amarillo, TX.

The interaction of CD28 with its counter-receptor, B7, induces a cosignal in T cells required to prevent clonal anergy and to promote antigen-dependent interleukin-2 production. The molecular basis of the CD28 cosignal is not well understood but involves the activation of protein tyrosine kinase(s) (PTK). In this report we demonstrate that CD28 cross-linking on Jurkat T leukemic cells causes the activation of at least two PTK pathways. Read More

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November 1994

Translational regulation by the interferon-induced double-stranded-RNA-activated 68-kDa protein kinase.

Proc Natl Acad Sci U S A 1993 May;90(10):4621-5

Department of Microbiology, School of Medicine, University of Washington, Seattle 98195.

Activation of the interferon-inducible 68-kDa protein kinase (referred to as P68) by double-stranded RNA catalyzes phosphorylation of the alpha subunit of eukaryotic protein synthesis initiation factor 2. We have analyzed the transient expression of mutant and wild-type kinase molecules in transfected COS cells to examine the effects of the kinase on gene expression in the absence of other interferon-induced gene products. The wild-type P68 kinase was expressed inefficiently whereas a catalytically inactive P68 was expressed at 30- to 40-fold higher levels. Read More

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Tumor suppressor function of the interferon-induced double-stranded RNA-activated protein kinase.

Proc Natl Acad Sci U S A 1993 Jan;90(1):232-6

Unit of Virology and Cellular Immunology, Centre National de la Recherche Scientifique, Institut Pasteur, Paris, France.

RNA-dependent protein kinase is a M(r) 68,000 protein in human cells (p68 kinase) or a M(r) 65,000 protein in murine cells (p65 kinase). p65/p68 is a serine/threonine kinase induced by interferon treatment and generally activated by double-stranded RNAs. Once activated, the known function of this kinase is inhibition of protein synthesis through phosphorylation of the eukaryotic initiation factor 2. Read More

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January 1993

Detection of protein kinase homologues and viral RNA-binding domains utilizing polyclonal antiserum prepared against a baculovirus-expressed ds RNA-activated 68,000-Da protein kinase.

Virology 1992 Dec;191(2):670-9

Department of Microbiology, School of Medicine, University of Washington, Seattle 98195.

The P68 protein kinase (referred to as P68 based on its M(r) of 68,000 in human cells) is a serine/threonine kinase induced by interferon treatment and activated by dsRNAs. The kinase is under tight controls in virus-infected cells since once activated, it phosphorylates its natural substrate eukaryotic initiation factor 2 (elF-2), leading to potential limitations in functional elF-2 and decreases in protein synthesis initiation. To further delineate the molecular mechanisms underlying kinase regulation, we attempted to express the P68 protein kinase in insect cells using a baculovirus vector. Read More

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December 1992

Constitutive expression of human double-stranded RNA-activated p68 kinase in murine cells mediates phosphorylation of eukaryotic initiation factor 2 and partial resistance to encephalomyocarditis virus growth.

J Virol 1992 Oct;66(10):5805-14

Unit of Virology and of Cellular Immunology (UA CNRS 1157), Institut Pasteur, Paris, France.

The cDNA encoding interferon-induced human double-stranded RNA-activated p68 kinase was expressed in murine NIH 3T3 cells by using the pcDNA1/neo vector. Several stable clones were selected which expressed either the wild-type kinase or an inactive mutant possessing a single amino acid substitution in the invariant lysine 296 in the catalytic domain II. The transfected wild-type kinase showed properties similar to those of the natural kinase, such as subcellular ribosomal localization and dependence on double-stranded RNA for autophosphorylation. Read More

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October 1992

Construction and expression of an enzymatically active human-mouse chimeric double-stranded RNA-dependent protein kinase.

R C Patel G C Sen

J Interferon Res 1992 Oct;12(5):389-93

Department of Molecular Biology, Cleveland Clinic Foundation, OH 44195-5285.

The interferon (IFN)-inducible double-stranded (ds) RNA-activated protein kinase (p68 kinase) is a physiologically important enzyme that regulates the rate of cellular and viral protein synthesis by phosphorylating and thereby inactivating the peptide chain initiation factor 2. We have generated a partial cDNA clone, which probably represents the murine p68 kinase, by reverse transcription-polymerase chain reaction (RT-PCR) using sequence information of the human p68 kinase. The 725-bp cDNA clone encoded the carboxyl-terminal 238 amino acid residues of the mouse kinase. Read More

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October 1992

Functional expression and RNA binding analysis of the interferon-induced, double-stranded RNA-activated, 68,000-Mr protein kinase in a cell-free system.

Mol Cell Biol 1991 Nov;11(11):5497-505

Department of Microbiology, School of Medicine, University of Washington, Seattle 98195.

Eukaryotic viruses have devised numerous strategies to downregulate activity of the interferon-induced, double-stranded (dsRNA)-activated protein kinase (referred to as p68 on the basis of its Mr of 68,000 in human cells). Viruses must exert this control to avoid extensive phosphorylation of the alpha subunit of eukaryotic initiation factor 2 (eIF-2) by p68 and the resultant negative effects on protein synthesis initiation. To begin to define the molecular mechanisms underlying this regulation, we optimized expression of p68 in an in vitro transcription-translation system utilizing the full-length cDNA clone. Read More

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November 1991