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)

Ultrastructural analysis of M-band from nuclei of rat liver showed small amounts of chromatin, fragments of inner nuclear membrane, some amorphous nuclear material, and nucleopores. The outer nuclear membrane with its associated ribosomes was removed by Sarkosyl during the preparation of M-band sample. Morphological features of nucleopores and the inner nuclear membrane were confirmed by freez-fracture technique. The gross chemical composition of the M-band was similar to that of nuclear-membrane fractions prepared by other techniques. The M-band contained the greatest proportion of newly-labeled DNA and also supported DNA synthesis in vitro. Electron-microscopic autoradiography of the M-band showed localization of silver grains of thymidine-3H presumably over newly synthesized DNA. The DNA synthesis could not be attributed to spurious attachment of DNA polymerase to M-band during its isolation. It was partially removed from the M-band by treatment with 0.5 M KC1, phospholipase A or C; and completely, by the action of pancreatic DNase. DNA synthesis was greater in M-band fractions isolated from nuclei of 24-hour regenerating liver.
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PMID:DNA synthesis associated with a DNA-nuclear-membrane complex from rat liver. 92 32

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

A method of mutagenic and unidirectional reassembly (MURA) that can generate libraries of DNA-shuffled and randomly truncated proteins was developed. The method involved fragmenting the template gene(s) randomly by DNase I and reassembling the small fragments with a unidirectional primer by PCR. The MURA products were treated with T4 DNA polymerase and subsequently with a restriction enzyme whose site was located on the region of the MURA primer. The N-terminal-truncated and DNA-shuffled library of a Serratia sp. phospholipase A(1) prepared by this method had an essentially random variation of truncated size and also showed point mutations associated with DNA shuffling. After high-throughput screening on triglyceride-emulsified plates, several mutants exhibiting absolute lipase activity (NPL variants) were obtained. The sequence analysis and the lipase activity assay on the NPL variants revealed that N-terminal truncations at a region beginning with amino acids 61 to 71, together with amino acid substitutions, resulted in the change of substrate specificity from a phospholipase to a lipase. We therefore suggest that the MURA method, which combines incremental truncation with DNA shuffling, can contribute to expanding the searchable sequence space in directed evolution experiments.
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PMID:Construction of DNA-shuffled and incrementally truncated libraries by a mutagenic and unidirectional reassembly method: changing from a substrate specificity of phospholipase to that of lipase. 1245 Aug 39