Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.7 (DNA polymerase)
 17,007 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Primer recognition proteins (PRP) enable DNA polymerase alpha to utilize efficiently DNA substrates with low primer to template ratios. We have previously identified the protein-tyrosine kinase substrate annexin II, and the glycolytic enzyme 3-phosphoglycerate kinase as components of PRP. As a step towards elucidation of the role of PRP in the process of DNA replication, we have investigated the subcellular distribution and specific association of these proteins with the nuclear matrix in HeLa cells. Nuclear extracts prepared from HeLa cells in S phase contain the enzymatic activity of 3-phosphoglycerate kinase (PGK) and phospholipase A2 inhibitory activity of annexin II. Monomer annexin II is approximately equally distributed between the nuclear and cytoplasmic fractions, while a majority of PGK is in the cytoplasm. Immunoblot analyses reveal the presence of these two proteins in nuclei, specifically associated with the nuclear matrix. This is further confirmed by observation of the presence of annexin II and PGK in isolated nuclear matrices by immunoelectron microscopy. The phospholipase A2 inhibitory activity of annexin II colocalizes with the nuclear matrix-bound annexin II. A related protein, annexin I, is not detectable in the nuclear extracts and nuclear matrix. A slower-migrating (perhaps modified) form of annexin II is found to be associated with the nuclear matrix. Attempts to dissociate PGK and annexin II from the nuclear matrix with octyl-beta-glucoside, high salt or metal ion chelators were unsuccessful, suggesting that the interaction is very strong.
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PMID:The role of primer recognition proteins in DNA replication: association with nuclear matrix in HeLa cells. 153 25

Primer recognition proteins (PRP) are cofactors for DNA polymerase alpha and may have a role in lagging-strand DNA replication. PRP is composed of two subunits, which we have previously identified as the protein-tyrosine kinase substrate annexin II and phosphoglycerate kinase (PGK). In this study, we have examined the physiological involvement of these proteins in DNA synthesis and cell proliferation. When exponentially growing human HeLa cells are exposed to antisense phosphorothioate oligodeoxynucleotides to annexin II, ongoing DNA synthesis is reduced. The extent of reduction with antisense oligodeoxynucleotide to PGK was much less than with the antisense annexin II oligodeoxynucleotide. Reductions in the labeling and mitotic indices of HeLa cell cultures are seen after exposure to antisense oligodeoxynucleotides. Flow cytometric analyses indicate that progression from S phase to G2 phase of the cycle is retarded by exposure of cells to the antisense oligodeoxynucleotides. Corresponding sense oligodeoxynucleotides have no inhibitory effects on these parameters. The new synthesis of annexin II and PGK is specifically reduced in the presence of antisense oligodeoxynucleotides, indicating that the complex of newly synthesized annexin II and PGK may participate in PRP function. These experiments indicate that annexin II and PGK may have a physiological role in DNA synthesis and cell cycle progression, and represent the first physiological role for annexin II monomer in cells.
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PMID:The role of primer recognition proteins in DNA replication: inhibition of cellular proliferation by antisense oligodeoxyribonucleotides. 153 26

Primer recognition proteins (PRP) stimulate the activity of DNA polymerase alpha on DNA substrates with long single-stranded template containing few primers. Purified PRP from HeLa cells and human placenta are composed of two subunits of 36,000 (PRP 1) and 41,000 (PRP 2) daltons. By amino acid sequence homology, we have identified PRP 2 as the glycolytic enzyme 3-phosphoglycerate kinase. Here we present data that establishes PRP 1 to be the protein-tyrosine kinase substrate, calpactin I heavy chain. Amino acid sequence analysis of six tryptic peptides of PRP 1 followed by homology search in a protein sequence data base revealed 100% identity of all six peptides with the deduced amino acid sequence of human calpactin I heavy chain. The activities of PRP and calpactin I coelute on gel filtration columns, and a high correlation of PRP and calpactin I activities was seen at different stages of purification. A rabbit polyclonal anti-chicken calpactin I antibody was shown to cross-react with PRP 1 polypeptide at various stages of PRP purification, and the homogeneous preparation of PRP exhibits 3-phosphoglycerate kinase (PRP 2) and calpactin I (PRP 1) activities. PRP activity is neutralized by a mouse monoclonal anti-calpactin II antibody although having no effect on the polymerase alpha activity itself. Calpactin II has a 50% amino acid sequence homology with calpactin I. However, PRP 1 is not calpactin II as shown by lack of cross-reaction to a monoclonal anti-calpactin II antibody on Western blots. Calpactin I and 3-phosphoglycerate kinase, purified independently, cannot be efficiently reconstituted into the PRP complex, indicating that their association in the PRP complex involves specific protein-protein interactions that remain to be elucidated. The biochemical and immunological data presented here revealing the identity of PRP 1 as calpactin I provide evidence for one physiological role of calpactin I in the cell.
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PMID:The protein-tyrosine kinase substrate, calpactin I heavy chain (p36), is part of the primer recognition protein complex that interacts with DNA polymerase alpha. 182 30

Primer recognition proteins (PRP) are accessory proteins for DNA polymerase alpha in lagging strand DNA replication. We have previously reported that the PRP consist of a complex of two proteins identified as 3-phosphoglycerate kinase (PGK) and the protein-tyrosine kinase substrate, annexin 2 monomer. The physiological role of annexin 2 is not known. Two pools of annexin 2 exist in cells. A majority of annexin 2 is localized with the plasma membrane as a heterotetramer in association with a light chain. Monomer annexin 2 is cytosolic. The identification of annexin 2 monomer as a part of the PRP complex represents one of the physiological roles of this protein in cells. To function as PRP, annexin 2 and PGK would have to be present in the cell nucleus. To investigate whether monomer annexin 2 is indeed associated with nuclear DNA synthesis, we investigated the presence of annexin 2 and PGK in the cell nucleus. In this paper, we demonstrate the presence of annexin 2 and PGK in nuclear extracts. The nuclear fraction of these proteins represents a small subset of the total cellular pools. Immunoelectron-microscopic analyses using anti-PRP antisera demonstrate the distribution of these proteins in HeLa cell nuclei and cytoplasm. Under identical conditions, an anti-cytokeratin monoclonal antibody preferentially labels the plasma membrane without detectable intracellular staining. The distribution of annexin 2 and PGK in both nuclei and cytoplasm is similarly observed in cells from normal tissues such as freshly isolated rat hepatocytes and hamster pancreatic tissue.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Immunoelectron microscopic analysis of the intracellular distribution of primer recognition proteins, annexin 2 and phosphoglycerate kinase, in normal and transformed cells. 183 52

Primer recognition proteins (PRP) are cofactors of DNA polymerase alpha and may have a role in lagging strand DNA replication. Purified PRP from HeLa cells and human placenta are composed of two subunits of 36,000 (PRP 1) and 41,000 (PRP 2) daltons. Upon tryptic digestion, amino acid sequencing of tryptic peptides, and homology search against a protein sequence data base, we have identified PRP 2 to be the glycolytic enzyme, phosphoglycerate kinase (PGK). The activities of PRP and PGK increase coordinately in the PRP purification procedure. PRP activity is inhibited by the PGK substrate 3-phosphoglycerate and the competitive inhibitor of substrate binding, DL-alpha-glycerol 3-phosphate. 5'-p-Fluorosulfonylbenzoyl adenosine, which inactivates PGK by binding to the nucleotide binding site, also inhibits PRP. For PRP activity, the two substrate binding sites of PGK are necessary in addition to the as yet unidentified PRP 1 polypeptide.
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PMID:Functional identity of a primer recognition protein as phosphoglycerate kinase. 232 90

Ganciclovir (9-[(1,3-dihydroxy-2-propoxy)methyl]guanine) is a potent inhibitor of viruses of the herpes family, including cytomegalovirus (CMV), that are pathogenic for humans and animals. The primary mechanism of ganciclovir action against CMV is inhibition of the replication of viral DNA by ganciclovir-5'-triphosphate (ganciclovir-TP). This inhibition includes a selective and potent inhibition of the viral DNA polymerase. Ganciclovir is metabolized to the triphosphate form by primarily three cellular enzymes: (1) a deoxyguanosine kinase induced by CMV-infected cells; (2) guanylate kinase; and (3) phosphoglycerate kinase. Other nucleotide-metabolizing enzymes may be involved as well. The selective antiviral response associated with ganciclovir treatment is achieved because of the much weaker inhibition of cellular DNA polymerases by ganciclovir-TP. Activity and selectivity are also amplified by the accumulation of ganciclovir-TP in CMV-infected cells.
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PMID:Antiviral activity and mechanism of action of ganciclovir. 284 85

Multiphasic kinetics are often observed in stopped-flow investigations. To characterize further these kinetic phases, we have developed a methodology whereby fluorescence total intensity and anisotropy stopped-flow data can be combined in a single analysis. Fluorescence total intensity and anisotropy are highly interrelated and contain two very complementary forms of information. Total-intensity changes are useful in determining changes in populations with differing quantum yields, whereas anisotropy changes contain additional contributions caused by the rotational dynamics of the species. For cases in which the fluorescence quantum yield increases, the observed rate of anisotropy change will be more rapid than the total-intensity change, whereas in cases in which the total intensity decreases, the observed change in anisotropy will lag behind. In all cases, with quantum yield changes the stopped-flow anisotropy signals cannot be fit with models consisting of exponentials. Case studies examining these effects are described for the protein folding/refolding transitions of Staphylococcal nuclease and phosphoglycerate kinase. A multiphasic DNA exonuclease reaction using bacteriophage T4 DNA polymerase is also examined. In all of these cases, combined analysis of both data types revealed insights into reaction mechanism, which could not be obtained by either data type in isolation. Quantum yields and steady-state anisotropies associated with transiently populated intermediate species can be resolved. The data analysis methodologies described allow characterization of multiphasic reactions in terms of internally consistent kinetic rates, quantum yields, and steady-state anisotropies.
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PMID:Resolution of multiphasic reactions by the combination of fluorescence total-intensity and anisotropy stopped-flow kinetic experiments. 769 90