Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.27.1 (RNase)
16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The oncogene product p53, isolated from SV3T3 cells where it forms a complex with simian virus 40 large tumor antigen (T antigen) in the nucleus, has been found to be phosphorylated at at least four distinct sites on the 390 amino acid protein. Separation of tryptic phosphopeptides has permitted identification of two sites as Ser-312 and Ser-389, and permitted analysis of the types of phosphate bonds. The peptide containing Ser-312 separates electrophoretically into three charged forms; two are resistant to dephosphorylation by both alkaline phosphatase and alkaline hydrolysis, suggesting a phosphodiester. The carboxyl-terminal phosphopeptide containing Ser-389 was alkaline phosphatase-resistant and liberated four ribonucleoside monophosphates upon base or RNase hydrolysis, suggesting that Ser-389 may be covalently linked to RNA. Phosphorylation of Ser-389 decreased markedly at the nonpermissive temperature in simian virus 40 tsA58-transformed cells, indicating a dependence on native T antigen function and a possible role in transformation by T antigen. Two additional phosphorylation sites, one involving serine and one involving threonine, probably reside in the amino-terminal segment of p53 and appear to be peptide-phosphate monoesters.
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PMID:Mapping of phosphomonoester and apparent phosphodiester bonds of the oncogene product p53 from simian virus 40-transformed 3T3 cells. 300 31

A nuclear p53/55 protein kinase has been isolated from nuclear ribonucleoprotein particles from human tumor cells. The enzyme was purified approximately 2200-fold cell nuclei by sequential ribonuclease digestion of the RNP particles, DEAE cellulose and phosphocellulose chromatography. The kinase which was cAMP independent, catalyzed the phosphorylation of rabbit muscle glycogen synthase in the amino terminal domain, and conversion of the I to D form. The D synthase had a phosphorylation stoichiometry of 8 moles 32P per mole of synthase subunit with maximal specificity for ATP as phosphate donor; its Km was 30 microM. An antinucleolar antibody inhibited enzyme activity by 80%. Substrates for most other kinases were inactive. The kinase was essentially unaffected by the Walsh inhibitor, EGTA, regulatory subunits of protein kinase, calmodulin, trifluoperazine or heparin. Its activity was lost at 1 mM polyamine, but was enhanced 3-fold by MnCl2 and 4- to 9-fold by deoxymononucleotides. The nuclei of HeLa cells contained 64% of the total kinase of which 64% of the total kinase of which 11% were in nucleoli; the specific activity of the nucleolar kinase was twice that of the nuclear supernatant and four times that of the cytoplasmic kinase. These results indicate that nucleolar ribonucleoprotein particles of human tumor cells contain a cAMP-independent protein kinase which is similar to glycogen synthase kinase.
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PMID:Purification of p53/55 kinase from nuclear ribonucleoproteins of Namalwa cells. 643 81

Although thyroid cancer tends to metastasize early in children, it is generally associated with a good prognosis. In this study, the expression of p53, mutations of which are found in many cancers, including anaplastic thyroid cancer, was examined to determine the relationship between cell proliferation and the clinical course of thyroid cancer. The clinicopathological findings and clinical courses of 15 children who underwent surgery before the age of 18 years at our hospital between 1972 and 1992 were examined, and the expression of p53 was studied using immunohistochemical techniques and an RNase protection assay. Postoperative follow-up ranged from 1 to 20 years, with a median of 12 years. No abnormal expression of p53 was detected in the thyroid cancer of any of the children tested, and none of them have died. The findings of this study therefore strongly suggest that p53 may play a role in the regulation of cell proliferation, and in this capacity slow the growth of and be related to the prognosis of differentiated thyroid cancer in children.
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PMID:Clinicopathological findings and p53 expression of thyroid cancer in children. 764 Apr 49

Pancreatic ductal adenocarcinomas induced in the Syrian golden hamster (SGH) by N-nitrosobis(2-oxopropyl)amine share many similarities with the human disease, including mutations of the K-ras oncogene. In vitro carcinogenesis studies with immortal SGH pancreatic duct cells indicate that neoplastic transformation in this system can occur without mutational inactivation of p53 suppressor gene. In this study we extend the genetic analysis of the in vivo SGH model to increase the number of cases analyzed for the status of K-ras and to determine further the spectrum of alterations involved; we have studied the status of the p53, DCC, and Rb-1 suppressor genes and the status of the mdm2 oncogene, which can involve p53 indirectly. The partial SGH-coding sequence of mdm2 and DCC was determined. K-ras mutation in the second position of codon 12 was present in 17 of 19 (90%) of tumors. Immunohistochemistry and single strand conformation polymorphism analysis showed no evidence of p53 mutation in 21 tumors. RNase protection assays showed overexpression of mdm2 in 5 of 19 (26%) tumors. Semiquantitative reverse transcription-PCR analysis showed a complete or partial loss of DCC expression in 10 of 19 (53%) neoplasms and of Rb-1 (42%) expression in 8 of 19 tumors when compared to matched controls. Deregulation of these genes appears to be significant in SGH pancreatic carcinogenesis as indicated by their frequencies. However, the fact that 6 tumors showed either only a K-ras mutation or the absence of alterations of the 5 genes analyzed indicates that additional as yet unstudied or unknown genes are also involved in SGH pancreatic duct carcinogenesis.
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PMID:Multiple genetic alterations in hamster pancreatic ductal adenocarcinomas. 778 Sep 69

The deleted in colorectal cancer (DCC) gene has been identified as a candidate tumor suppressor gene on the basis of frequent allelic loss and decreased or absent gene expression in several human cancer types, as well as somatic mutations in the gene in colorectal tumors. We have identified a Xenopus DCC homologue (XDCC alpha) predicted to encode a protein of 1427 amino acids and have characterized XDCC expression in developing embryos and adult tissues. The predicted amino acid sequences of XDCC alpha and human DCC are greater than 80% identical; each has four immunoglobulin-like domains, six fibronectin type III domains, and a cytoplasmic domain of about 325 amino acids. While RNase protection assays and immunoblotting studies failed to detect XDCC alpha expression in embryos prior to developmental stage 15, XDCC alpha expression was present in embryos from stages 19 to 46. Whole mount in situ hybridization studies localized XDCC alpha expression to developing forebrain, midbrain, and hindbrain regions. DCC expression was inhibited by treatments that altered the development of mature neural structures; specifically, uv-ventralized embryos and exogastrulae had reduced DCC expression. These results indicate that XDCC alpha is developmentally regulated and expressed as a consequence of neural induction. Moreover, unlike some well-characterized tumor suppressor genes, such as the p53 and retinoblastoma genes, that are not differentially expressed in developing Xenopus embryos, the DCC gene may have a specific role in the morphogenesis of the brain and perhaps other tissues and organs.
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PMID:Expression of a homologue of the deleted in colorectal cancer (DCC) gene in the nervous system of developing Xenopus embryos. 781 84

The quaternary structure of the adenovirus early region 1B 54K protein has been examined under denaturing and nondenaturing conditions. In the presence of SDS the protein has a strong tendency to form disulfide-linked high-molecular-weight polymers. Under nondenaturing, but reducing, conditions the in vitro-translated 54K polypeptide forms oligomers (probably tetramers) of molecular weight approximately 2 x 10(5). After subcellular fractionation of Ad12 early region 1-transformed cells, the 54K E1B protein present in the cytoplasm had a molecular weight similar to that determined for the in vitro-translated material. However, two populations of the viral protein could be distinguished in the nucleus-one of a size similar to that seen in the cytoplasm and the other of appreciably higher molecular weight (approximately 2 x 10(6)). No difference in migration pattern was observed after treatment of the nuclear extract with DNase I or RNase. A proportion of the Ad12 E1B 54K protein in both the high- and the low-molecular-weight populations in the nucleus was found to form a complex with p53, and it is therefore concluded that the very high molecular weight derives from interaction with an, as yet, unidentified component.
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PMID:The quaternary structure of the adenovirus 12 early region 1B 54K protein. 787 36

Previously, increased expression of mRNA encoding the p53 tumor suppressor protein was described during castration-induced regression of the rat ventral prostate gland with Northern blot techniques. This activity was confirmed with a ribonuclease protection assay that demonstrated a 16-fold induction of p53 transcripts in ventral prostate RNA within 72 hrs after castration. The induced expression of p53 mRNA correlated with increased detection of p53 protein in nuclei of regressing prostate epithelial cells. Immunohistochemical staining with anti-p53 antibody was strongly reactive for epithelial nuclei in castrated glands but unreactive for nuclei of control adult glands. In contrast to the upregulation of p53 in regressing prostate glands with a large proportion of apoptotic cells, expression of p53 mRNA was decreased in rat prostate glands that were stimulated to regrow by testosterone replacement.
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PMID:Enhanced expression of p53 mRNA and protein in the regressing rat ventral prostate gland. 790 41

A plasmid carrying the 5' flanking region of the mouse proliferating-cell-nuclear-antigen (PCNA) gene or DNA polymerase beta gene was fused with the chloramphenicol acetyltransferase (CAT) gene, then cotransfected into mouse N18TG2 cells with the expression plasmid for the p53 gene. Expression of the wild-type p53 repressed the CAT expression directed by the PCNA gene promoter, while it had little effect on the DNA polymerase beta gene promoter. RNase protection analysis revealed that the repression of the PCNA gene promoter by p53 was at the transcription step. Analysis with various deletion mutants in the PCNA gene promoter revealed that a specific sequence is not required for the repression, suggesting that p53 represses the PCNA gene promoter by interacting with some components of the basic transcription machinery. By analysis with various deletion mutants in the DNA polymerase beta gene promoter, we identified the unique 10-bp palindromic sequence (-24 to -15), in the presence of which p53 was not able to repress the promoter activity. This sequence conferred resistance to p53 repression onto the PCNA gene promoter, when it was placed 21-bp upstream from the transcription-initiation site.
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PMID:Differential effect of p53 on the promoters of mouse DNA polymerase beta gene and proliferating-cell-nuclear-antigen gene. 790 18

We have studied the abilities of different transactivation domains to stimulate the initiation and elongation (postinitiation) steps of RNA polymerase II transcription in vivo. Nuclear run-on and RNase protection analyses revealed three classes of activation domains: Sp1 and CTF stimulated initiation (type I); human immunodeficiency virus type 1 Tat fused to a DNA binding domain stimulated predominantly elongation (type IIA); and VP16, p53, and E2F1 stimulated both initiation and elongation (type IIB). A quadruple point mutation of VP16 converted it from a type IIB to a type I activator. Type I and type IIA activators synergized with one another but not with type IIB activators. This observation implies that synergy can result from the concerted action of factors stimulating two different steps in transcription: initiation and elongation. The functional differences between activators may be explained by the different contacts they make with general transcription factors. In support of this idea, we found a correlation between the abilities of activators, including Tat, to stimulate elongation and their abilities to bind TFIIH.
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PMID:Three functional classes of transcriptional activation domain. 862 70

We have isolated, sequenced, and characterized a human MN/CA9 gene. This gene is a novel member of the carbonic anhydrase (CA) family, which codes for widely distributed catalysts of the reversible conversion of carbon dioxide to carbonic acid. So far, MN/CA IX is the only tumor-associated CA isoenzyme. The entire genomic sequence of MN/CA9, including the 5'-flanking region, encompasses 10.9 kb. The coding sequence is divided into 11 exons, whose organization and relationships to predicted protein domains suggest that the gene arose by exon shuffling. Exon 1 encodes a signal peptide and a proteoglycan-related region. Exons 2-8 code for a CA domain with a highly conserved active site. The exon/intron pattern of the CA coding region is similar but not identical to other described animal kingdom alpha-CA genes. Exons 10 and 11 encode a transmembrane anchor and an intracytoplasmic tail, respectively. We have also determined the transcription initiation and termination sites by RNase protection assay and analyzed the 3. 5-kb region upstream of the MN/CA9 gene. Sequence of the proximate 5' end of the flanking region shows extensive homology to the long terminal repeats of HERV-K endogenous retroviruses. The putative MN/CA9 promoter immediately preceding the transcription start site does not possess a TATA box, but contains consensus sequences for the AP1, AP2, p53, and Inr transcription factors. This study will allow further investigations of the molecular events regulating expression of MN/CA IX as well as elucidation of its biological function.
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PMID:Human MN/CA9 gene, a novel member of the carbonic anhydrase family: structure and exon to protein domain relationships. 866 Oct 7


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