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)

The restriction endonuclease sites in and around the human gamma globin gene loci have been mapped using the gel blotting technique of Southern, in both normal DNA and DNA from an individual with hereditary persistence of fetal hemoglobin (HPFH). In normal DNA, the gamma genes are linked to the delta (and beta) globin genes, and the orientation of these genes with respect to transcription is (5') G gamma leads to A gamma leads to delta leads to beta (3'). The distance between the G gamma and A gamma genes is 3.5 kb and that between the A gamma and delta genes is 16 kb. In both normal DNA and HPFH DNA, the gamma genes are interrupted by an intervening sequence, approximately 1 kb in length that is situated between codon positions 99 and 121 of the coding sequence. In different DNA samples, there is polymorphism for the presence or absence of a Hind III site in the intervening sequence of either gamma golbin gene. In HPFH DNA, a deletion of at least 16 kb of DNA has been detected. This deletion starts at a point approximately 12.5 kb from the 3'-end of A gamma gene and extends through the delta and beta globin genes to a point at least 3 kb beyond the 3'-end of beta globin gene.
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PMID:Restriction endonuclease mapping of the human gamma globin gene loci. 46 Nov 96

The percentage of G gamma chains in the Hb F of SS patients and beta-thalassemia heterozygotes is generally 40%, but some have 60% to 70% G gamma. To test the hypothesis that DNA sequence variation 158 base pairs 5' of the G gamma gene is associated with this variation in G gamma values, DNA was analyzed using the restriction endonuclease Xmn I (gamma IVS-II probe). Xmn I recognizes the sequence from -157 to -166 only if T is at position -158. Individuals from five families had T at -158 for G gamma genes in both chromosomes, and the mean G gamma value was 69.7% +/- 4.6% (SD). For 13 families, individuals with T at -158 for the G gamma gene of one chromosome had a G gamma value of 60.6% +/- 5.7%. With one exception, lack of T at -158 was associated with low G gamma values (39.6% +/- 4.0%). In low Hb F G gamma-beta+-HPFH, the Xmn I site was seen 5' to both G gamma and A gamma genes, which suggests that T at -158 is associated with elevated Hb F; Pst I digestion showed that the A gamma gene T producer G gamma globin, which accounts for high levels of G gamma (87-88%). Calculations show that T at -158 is associated with a three- to 11-fold increase in production per G gamma gene, which is an order of magnitude less than that associated with the previously identified -202 C----G substitution of high Hb F G gamma-beta+-HPFH.
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PMID:DNA sequence variation associated with elevated fetal G gamma globin production. 241 16

The first example of a deletion of one of the two gamma globin genes has been characterized through an analysis of the DNA of the heterozygous parent of a homozygous newborn, using restriction endonuclease mapping techniques. A deletion of approximately 5 kb was observed which was probably caused by an unequal crossing-over between the -G gamma- and -A gamma- genes resulting in the formation of a -G gamma A gamma- hybrid gene. Data on proportions of G gamma and A gamma chains in newborn babies assumed to be heterozygous for the hybrid and normal genes suggest that this hybrid gene may be producing its A gamma chain at levels normally seen only for the G gamma chain.
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PMID:Gamma thalassemia resulting from the deletion of a gamma-globin gene. 630 96

The restriction endonuclease map of the alpha and beta globin genomic region of the new human erythroleukemia line, HEL, was compared with that of normal human DNA. The HEL line, which produces mainly fetal (G gamma and A gamma) but no adult (delta and beta) globin chains, was shown to have the same pattern of DNA fragments as that of normal human DNA. This suggests that the selective expression of the gamma globin genes observed in HEL cells is not due to a major deletion or rearrangement in the epsilon-G gamma-A gamma-delta-beta gene complex. Thus, the HEL line provides a model for studying the control of globin developmental switching in cells with structurally intact globin gene regions.
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PMID:Restriction endonuclease mapping of globin genomic regions of HEL (human erythroleukemia) line. 630 30

Nuclear DNA is organised into loops, probably by attachment to a supramolecular structure. We describe a method which enables us to map the position of sequences within a loop relative to the point of attachment. Nuclear DNA is isolated unbroken by lysing HeLa cells in 2M NaCl to release structures which retain many of the morphological features of nuclei. Their DNA is supercoiled and so must remain unbroken and looped during lysis. Nucleoids are digested to various degrees with a restriction endonuclease and the cages - and any associated DNA - sedimented free from unattached DNA. The cage-associated DNA is purified and completely fragmented using the same restriction endonuclease. Equal weights of fragmented DNA are separated by gel electrophoresis, transferred to a filter and the relative amounts of the alpha, beta and gamma globin genes on the filter determined by hybridisation to the appropriate probes. The alpha genes, unlike the beta and gamma genes, resist detachment from the cage and so must lie close to the point of attachment to the cage. Our ability to map these genes implies that sequences cannot be attached at random to the cage; rather, specific sequences must be attached, so looping the DNA.
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PMID:Mapping sequences in loops of nuclear DNA by their progressive detachment from the nuclear cage. 743 96