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:3.1.30.2 (endonuclease)
18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ten astrocytomas were tested for gene amplification or rearrangement utilizing distinct probes to nine different oncogenes by Southern hybridization. The probes spanned the four major protein-coding classes of oncogenes; growth factor proteins (csis); growth factor receptor/tyrosine kinase-related proteins [erbB1 (epidermal growth factor receptor, EGF-R), neu (HER2/neu, erbB2), mos, yes]; nuclear binding proteins (c-myc, c-fos); and guanosine 5'-triphosphate binding proteins (N-ras, H-ras). Three astrocytomas, all glioblastomas, showed amplification of EGF-R-related sequences, and two of these amplifications were rearranged. Both rearrangements appeared similar by two different restriction endonucleases. Our findings suggest that it is primarily the EGF-R protooncogene (erbB1) that is amplified or rearranged in astrocytic neoplasms. No other oncogenes were amplified or rearranged, although EGF-R and neu cross-hybridization produced a "pseudo-rearranged" pattern for neu in EGF-R-amplified cases. The similar EGF-R restriction endonuclease abnormalities seen in two patients warrant further study.
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PMID:Oncogene abnormalities in astrocytomas: EGF-R gene alone appears to be more frequently amplified and rearranged compared with other protooncogenes. 167 68

Hemoglobin H disease is often caused by deletion of three of the four alpha-globin genes (genotype: --/-alpha). We studied a Japanese girl who had microcytic hypochromic anemia, a decreased alpha/beta globin synthetic ratio and about 8% Hb H in her fresh hemolysate, by means of restriction endonuclease mapping of the alpha-like gene complex (5'-zeta-phi zeta-phi alpha 2-phi alpha 1-alpha 2-alpha 1-theta-3') with zeta- and alpha-specific probes. It was found that the defect of one chromosome was associated with the removal of about 18 kb of DNA, known as --SEA type alpha-thalassemia-1, including the deletion of the part of phi alpha 2, phi alpha 1, alpha 2, alpha 1, and theta globin genes, while the other one was associated with the removal of 3.7 kb of DNA, known as rightward deletion type alpha-thalassemia-2. The results of a family study demonstrated that the deletion haplotype --SEA was inherited from her father's side and the other -alpha 3.7 from her mother's side.
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PMID:[The molecular basis of HbH disease in a Japanese girl]. 261 58

We have determined the molecular characteristics of alpha-thalassemia in 12 HbH subjects from Taiwan by restriction endonuclease mapping with alpha- and zeta-specific probes. We have found four types of defects in the alpha-thalassemia-2 genetic determinant: -alpha 3.7 type I; -alpha 4.2; alpha CS alpha; and alpha alpha T. All HbH subjects carried the --SEA genotype in the alpha-thalassemia-1 determinant. At least two different subtypes of --SEA genotype were observed in this study.
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PMID:The molecular basis of HbH disease in Taiwan. 282 23

A functional thymidine kinase (TK; ATP:thymidine 5'-phosphotransferase, EC 2.7.1.21) gene has been molecularly cloned from human DNA. The gene was rescued from a genomic library of TK-deficient mouse L cells transformed to the TK+ phenotype with total HeLa cell DNA. Of 14 overlapping clones, only one contained the intact human TK gene. The cloned recombinant bacteriophage carries a 16-kilobase insert derived entirely from human DNA and is capable of transforming LTK- cells to TK+ with an efficiency of 10 TK+ colonies per ng of DNA per 10(6) cells. Restriction endonuclease mapping shows that the functional human TK gene is at least twice as long as that reported for chicken. A 1.6-kilobase Xho I/EcoRI fragment was subcloned and found to hybridize to a human mRNA of 1.5 kilobases. When introduced into LTK- cells, the cloned human TK gene is regulated in the cell cycle-specific manner characteristic of TK+ mammalian cells. That is, TK activity in synchronized cells increases markedly with the onset of DNA synthesis. The signals governing the S-phase induction of TK activity reside within 16 kilobases of human DNA and are correctly interpreted by mouse cells.
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PMID:Molecular cloning and cell cycle-specific regulation of a functional human thymidine kinase gene. 657 46

In this report we present an experimental scheme that facilitates the study of homologous recombination between closely linked genes in cultured mammalian cells. Two different Xho I linker insertion mutants of the herpes simplex virus type 1 thymidine kinase (HTK) gene were introduced into mouse LTK- cells as direct repeats on a plasmid carrying a dominant selectable marker. Following stabilization of these sequences in the recipient cell, selection for TK+ was applied to detect recombinational events between different TK- genes. TK+ segregants were observed at a frequency of 10(-4)-10(-5) in lines harboring both mutant genes. Control lines carrying only one type of mutant HTK gene yielded TK+ cells at frequencies of 10(-7) or less. Physical analysis of the TK+ segregants has revealed the presence of an apparently normal HTK gene that is resistant to Xho l endonuclease digestion in each TK+ line examined. Analyses of the TK gene pairs before and after recombination suggest that at least 50% of the recombinants are the result of nonreciprocal exchanges of genetic information, or gene conversion events.
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PMID:Evidence for intrachromosomal gene conversion in cultured mouse cells. 657 76

The RET proto-oncogene, a receptor tyrosine kinase, has been evaluated as a candidate gene for multiple endocrine neoplasia type 2A and type 2B (MEN 2A and MEN 2B), for familial medullary thyroid carcinoma (FMTC), and for sporadic cases of medullary thyroid carcinoma (MTC) and pheochromocytomas. We determined the genomic structure of RET and used single-strand conformational polymorphism (SSCP) analysis to identify sequence variants in genomic DNA from families segregating MEN 2 and FMTC. In addition, we examined paired tumour and lymphocyte genomic DNAs from individuals with sporadic cases of MTC and pheochromocytoma. Altogether, we and others found 21 missense mutations in five cysteines clustered in the extra-cellular domain of RET (exons 10 and 11) associated with 111 MEN 2A and FMTC families. In contrast, a single point mutation that results in the substitution of threonine for methionine within the catalytic core of the tyrosine kinase domain (codon 918, exon 16) is responsible for all 66 reported cases of MEN 2B. Two missense mutations and a six base-pair deletion were identified in MTC tumour DNA, but no mutations were identified from pheochromocytoma tumour DNAs. A predictive DNA test for MEN 2A-associated mutations in RET has been developed that is based on detection of missense mutations by polymerase chain reaction (PCR) amplification and restriction endonuclease cleavage. A dominant oncogene model for the action of the RET gene product is proposed as a mechanism of action in MEN 2A, MEN 2B, FMTC and for at least some cases of sporadic MTC.
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PMID:The RET proto-oncogene and cancer. 759 67

Multiple endocrine neoplasia type 2A (MEN2A) and familial medullary thyroid carcinoma (FMTC) are autosomal dominant inherited cancer syndromes with incomplete penetrance. Following the identification of mutations in the RET proto-oncogene that segregate with the disease phenotype in MEN2A, MEN2B, and FMTC, genetic screening of individuals with mutations in RET may be performed. We have employed restriction endonuclease digestion of polymerase chain reaction products as an alternative to sequence analysis for rapid identification of mutant gene carriers in families in which MEN2A and FMTC are segregating. Twenty-one Australasian MEN2A and FMTC families have been screened for mutations in a cysteine-rich region of the RET proto-oncogene. Seven independent mutations were identified in key individuals in 16 of these families. We have identified a mutation in codon 620, 2053 T-->C (Cys620Arg), and two mutations in codon 634 of exon 11 of RET, 2095 T-->C (Cys634Arg) and 2096 G-->A (Cys634Tyr), all three of which were present in both MEN2A and FMTC families.
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PMID:A rapid screening method for the detection of mutations in the RET proto-oncogene in multiple endocrine neoplasia type 2A and familial medullary thyroid carcinoma families. 783 99

Although several tyrosine kinase-type growth factor receptors have been demonstrated in human colonic epithelial cells, the full spectrum of growth factor receptors has not been identified. Low stringency screening of a complementary DNA library prepared from the human colon cancer-derived cell line HT-29 with a probe containing the tyrosine kinase domain of human c-src kinase led to the identification and isolation of a clone containing a receptor class tyrosine kinase. This putative receptor was found to be identical to the human fibroblast growth factor receptor 3 (FGFR3) except for a region of 150 nucleotides (50 amino acids) encoding the presumptive ligand-binding domain, where it exhibited only 32% homology with the previously described FGFR3. The variant domain corresponded precisely to the splicing junctions of the exon encoding the carboxyl terminal half of the third immunoglobulin-like domain, suggesting that two forms of FGFR3 result from splicing of alternate exons in a manner similar to that previously found for FGFR1 and FGFR2. By prior convention, the previously reported from of FGFR3 was designated IIIc due to its high degree of homology with the IIIc domain of FGFR1 (83% homology) and the IIIc domain of FGFR2 (81% homology). However, the ligand-binding domain of FGFR3 found in the HT-29 cell line was more highly divergent from all previously reported FGFR immunoglobulin-like domain IIIs than any other two members of this receptor family. Therefore, we propose to designate the newly reported form as the FGFR3 IIIb variant. Genomic polymerase chain reaction confirmed that the IIIb-containing exon occupies a position 5' relative to the IIIc-containing exon within the FGFR3 gene. Northern blot analysis using a probe encompassing sequences unique to the FGFR3 IIIb mRNA confirmed the expression of a 4.4-kilobase transcript in two colon cancer-derived cell lines as well as normal human colonic mucosa. Using a technique combining reverse transcriptase polymerase chain reaction with restriction endonuclease digestion, cell lines, primary cells, and tissues were assessed for IIIb and IIIc transcripts; expression of the IIIb variant was associated with an epithelial lineage, while the IIIc variant was expressed predominantly in nonepithelial cells and tissues.
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PMID:Identification of a novel variant form of fibroblast growth factor receptor 3 (FGFR3 IIIb) in human colonic epithelium. 792 41

A new type II restriction endonuclease, XspI, was purified 11-fold in seven steps to homogeneity from Xanthomonas sp. strain YK1 grown aerobically in Luria broth. The final specific activity of the purified enzyme was 3890 micrograms of lambda DNA digested per h per mg of protein. The molecular weight of the native enzyme was determined to be 54,000. Sodium dodecyl sulfate-gel electrophoresis revealed two identical subunits of molecular weight 29,000. The purified enzyme was most active at 37 degrees C in the presence of 100 mM KCl and 5 mM MgCl2 under pH range from 7.5 to 8.0. The enzyme was stable at least for 1 h at 37 degrees C, but was inactivated after 20 min at 65 degrees C. XspI recognized the tetranucleotide sequence, 5'-CTAG-3', and cleaved it between C and T, like its isoschizomers MaeI and BfaI. The ability of the source organism to grown aerobically, together with the heat inactivation of the enzyme, confers practical advantages upon XspI over its known isoschizomers.
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PMID:XspI, a new type II restriction endonuclease from a Xanthomonas species. 966 77

Incubation of gradient purified human spermatozoa, which are routinely maintained in media prior to IVF and intracytoplasmic sperm injection (ICSI), induced DNA strand breaks (up to 89 nicks x 10(-3) bp) and chromatin release. Unlike highly dispersed Alu repeat sequences, the centromeric heterochromatin was much less susceptible to endonuclease attack. In addition to chromatin release, the permeability of the sperm membrane was altered as evidenced by reduced accessibility of sperm nuclei to decondensation factors in mouse embryo extracts. Hybridization of cDNA microarrays with DNA released from spermatozoa revealed a consistent hypersensitivity of certain genes to endogenous cleavage including TP53, VHL (tumour suppressors), BRCA1 (breast cancer), NOS1 (neurotransmitter), PECAM1, FLT1 (angiogenesis) and CDKN1C (cell cycle/imprinted). N-tert-butyl hydroxylamine (NTBH), a derivative of the anti-teratogenic alpha-phenyl-N-t-butyl nitrone (PBN) and synthetic superoxide dismutase (SOD)/catalase mimetics inhibited chromatin release and sustained or dissipated relative mitochondrial membrane potential. Together, these results show a link between the hyperactivation of sperm mitochondria and chromosomal damage of specific genes in vitro, and that the potential risk of disruption of paternally contributed genes can be circumvented by antioxidants which are known to target mitochondria.
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PMID:Gene-specific chromatin damage in human spermatozoa can be blocked by antioxidants that target mitochondria. 1465 2


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