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:1.6.99.5 (NADH dehydrogenase)
2,135 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The sequence of 13.9 kilobases (kb) of the 17.1-kb mitochondrial genome of Mytilus edulis has been determined, and the arrangement of all genes has been deduced. Mytilus mitochondrial DNA (mtDNA) contains 37 genes, all of which are transcribed from the same DNA strand. The gene content of Mytilus is typically metazoan in that it includes genes for large and small ribosomal RNAs, for a complete set of transfer RNAs and for 12 proteins. The protein genes encode the cytochrome b apoenzyme, cytochrome c oxidase (CO) subunits I-III, NADH dehydrogenase (ND) subunits 1-6 and 4L, and ATP synthetase (ATPase) subunit 6. No gene for ATPase subunit 8 could be found. The reading frames for the ND1, COI, and COIII genes contain long extensions relative to those genes in other metazoan mtDNAs. There are 23 tRNA genes, one more than previously found in any metazoan mtDNA. The additional tRNA appears to specify methionine, making Mytilus mtDNA unique in having two tRNA(Met) genes. Five lengthy unassigned intergenic sequences are present, four of which vary in length from 79 to 119 nucleotides and the largest of which is 1.2 kb. The base compositions of these are unremarkable and do not differ significantly from that of the remainder of the mtDNA. The arrangement of genes in Mytilus mtDNA is remarkably unlike that found in any other known metazoan mtDNA.
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PMID:A novel mitochondrial genome organization for the blue mussel, Mytilus edulis. 138 86

The nucleotide sequences of the mitochondrial DNA (mtDNA) molecules of two nematodes, Caenorhabditis elegans [13,794 nucleotide pairs (ntp)], and Ascaris suum (14,284 ntp) are presented and compared. Each molecule contains the genes for two ribosomal RNAs (s-rRNA and l-rRNA), 22 transfer RNAs (tRNAs) and 12 proteins, all of which are transcribed in the same direction. The protein genes are the same as 12 of the 13 protein genes found in other metazoan mtDNAs: Cyt b, cytochrome b; COI-III, cytochrome c oxidase subunits I-III; ATPase6, Fo ATPase subunit 6; ND1-6 and 4L, NADH dehydrogenase subunits 1-6 and 4L: a gene for ATPase subunit 8, common to other metazoan mtDNAs, has not been identified in nematode mtDNAs. The C. elegans and A. suum mtDNA molecules both include an apparently noncoding sequence that contains runs of AT dinucleotides, and direct and inverted repeats (the AT region: 466 and 886 ntp, respectively). A second, apparently noncoding sequence in the C. elegans and A. suum mtDNA molecules (109 and 117 ntp, respectively) includes a single, hairpin-forming structure. There are only 38 and 89 other intergenic nucleotides in the C. elegans and A. suum mtDNAs, and no introns. Gene arrangements are identical in the C. elegans and A. suum mtDNA molecules except that the AT regions have different relative locations. However, the arrangement of genes in the two nematode mtDNAs differs extensively from gene arrangements in all other sequenced metazoan mtDNAs. Unusual features regarding nematode mitochondrial tRNA genes and mitochondrial protein gene initiation codons, previously described by us, are reviewed. In the C. elegans and A. suum mt-genetic codes, AGA and AGG specify serine, TGA specifies tryptophan and ATA specifies methionine. From considerations of amino acid and nucleotide sequence similarities it appears likely that the C. elegans and A. suum ancestral lines diverged close to the time of divergence of the cow and human ancestral lines, about 80 million years ago.
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PMID:The mitochondrial genomes of two nematodes, Caenorhabditis elegans and Ascaris suum. 155 72

In a unique Chinese hamster mutant, Gal-32, the mitochondrially encoded subunits of cytochrome c oxidase (CO I, II, III) and NADH dehydrogenase (ND 1-6) are greatly decreased while other mitochondrially synthesized proteins, such as ATPase subunits 6 and 8, are less affected. Pulse-chase experiments with [35S]methionine demonstrated that the reduced amounts of CO I and ND 5 subunits in Gal-32 are not the result of more rapid protein degradation. No differences in sizes of mtRNAs were detected between wild type and mutant using Northern blotting. The steady state levels of both heavy and light strand mtDNA transcripts were elevated in Gal-32: CO I mRNA was 1.5-fold higher in the mutant than in the wild type; ND 5 mRNA was 1.9-fold higher; ND 6 precursor RNAs were 1.4-fold higher and ATPase 6 and 8 mRNA (a single transcript) was 2.7-fold higher. Thus, the amounts of translation products are roughly correlated with the levels of mRNAs. The reduced levels of mitochondrially synthesized proteins in Gal-32 are the result of decreased translation of specific mRNAs, not increased degradation of mtRNAs.
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PMID:Elevated mitochondrial RNA in a Chinese hamster mutant deficient in the mitochondrially encoded subunits of NADH dehydrogenase and cytochrome c oxidase. 169 38

Products of the mitochondrial genome were identified in the bovine kidney cell line NBL-1 by labelling with [35S]methionine in the presence of cycloheximide. Seven proteins were precipitated by an antiserum to bovine heart NADH dehydrogenase, corresponding to the seven mitochondrial gene products identified in the human HeLa cell line. Comparison of these mitochondrial gene products with purified bovine NADH dehydrogenase by SDS/gel electrophoresis revealed that the ND-5 product is probably a previously unidentified protein of apparent Mr 51,000, and the ND-4 product is the protein of apparent Mr 39,000.
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PMID:Identification of the subunits of bovine NADH dehydrogenase which are encoded by the mitochondrial genome. 230 23

The assembly of mitochondrially and cytoplasmically translated subunits of NADH dehydrogenase in the inner mitochondrial membrane was studied in rat hepatoma cultures. A polyclonal antibody to the purified bovine heart holoenzyme, which reacted with comigrating proteins of both rat liver and hepatoma mitochondria on immunoblots, precipitated 25-30 [35S]methionine-labeled proteins from hepatoma cell lysates. Six of these were sensitive to an inhibitor of mitochondrial translation (chloramphenicol), resistant to an inhibitor of cytosolic translation (cycloheximide), and were not present in cytochrome oxidase. By these criteria, six NADH dehydrogenase subunits are identified as being translated on mitochondrial ribosomes. The metabolic properties of the three most prominent of these at 51, 43, and 11 kDa were studied in more detail. Mitochondrial and nuclear-coded polypeptides assemble into NADH dehydrogenase at different rates as measured by incorporation of pulse-labeled proteins into immunoprecipitable enzyme. Nuclear-coded, imported polypeptides appear immediately after a pulse with [35S]methionine and retain constant stoichiometry. Mitochondrially coded proteins, although rapidly translated, appear at peak levels at different times between 0 and 12 h of chase in the immunoprecipitated enzyme. Ongoing synthesis and import of nuclear-coded proteins is necessary for mitochondrially coded proteins to be assembled. Excess, unassembled mitochondrially translated subunits are degraded in an oligomycin-sensitive manner. These data are consistent with a model in which a scaffold of imported proteins forms the inner core of the enzyme, and later arriving mitochondrially translated proteins attach to the scaffold in a time-dependent manner.
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PMID:Respiratory chain-linked NADH dehydrogenase. Mechanisms of assembly. 239 60

The present study demonstrates that the bovine cardiac sarcolemma possesses an NAD(P)H dehydrogenase activity which is able to oxidize both NADH and NAD(P)H in the presence of vanadate as an electron acceptor. The NADH dehydrogenase activity was significantly higher than the NAD(P)H dehydrogenase activity and both of them were almost completely inhibited by superoxide dismutase and atebrin and markedly reduced by the addition of the protonophore 2,4-dinitrophenol. The incubation of the sarcolemma in the presence of 10(-10), 10(-9), 10(-8) M methionine-enkephalin, a prevalent delta-opioid receptor agonist, or dynorphin A (1-17), a prevalent kappa-receptor agonist, produced a dose-dependent increase in the NAD(P)H dehydrogenase activity, with 10(-10) and 10(-9) M dynorphin A (1-17) more effective than the corresponding doses of methionine-enkephalin. The preincubation of the sarcolemma in the presence of superoxide-dismutase, atebrin or 2,4-dinitrophenol strongly inhibited the opioid-stimulated dehydrogenase activity. The stimulatory action elicited by 10(-8) M methionine-enkephalin or dynorphin A (1-17) was completely antagonized by 10(-8) M naloxone or Mr 1452, respectively, whilst 10(-8) M naloxone exerted only a partially antagonistic action against the effect produced by 10(-8) M dynorphin A (1-17), significantly more accentuated than the action of 10(-8) M Mr 1452 versus the same dose of methionine-enkephalin.
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PMID:Opioids stimulate sarcolemmal NAD(P)H-vanadate dehydrogenase activity. 290 34

The bovine mitochondrial gene products ND2 and ND4, components of NADH dehydrogenase, have been purified from a chloroform/methanol extract of mitochondrial membranes, and the human mitochondrial gene products ND2 and cytochrome b have been obtained by similar procedures. They have been identified by comparison of their amino-terminal protein sequences with those predicted from DNA sequences of bovine and human mitochondrial DNA. All of the proteins have methionine as their amino-terminal residue. In bovine ND2, this residue is encoded by the "universal" isoleucine codon AUA, and the sequences of human cytochrome b and bovine ND2 demonstrate that AUA also encodes methionine in the elongation step of mitochondrial protein synthesis. In human ND2, the amino-terminal methionine is encoded by AUU, which, as in the "universal" genetic code, is also used as an isoleucine codon in elongation. Thus, AUU has a dual coding function which is dependent upon its context.
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PMID:Initiation codons in mammalian mitochondria: differences in genetic code in the organelle. 296 65

Two types of defective mitochondrial DNA molecules with large deletions (5 kbp and 40 kbp) have previously been identified in the stopper mutant, E35, of Neurospora crassa. The junction fragments spanning the deletion endpoints have now been cloned and sequenced, and their sequences compared with those of the corresponding wild-type fragments. We show that both types of defective mitochondrial DNAs result from deletions of sequences flanked by short direct repeats, which are themselves parts of larger inverted repeat sequences. In every case, the short direct repeat sequences consist of a run of pyrimidines in one strand and purines in the other. We also report the sequence of a 2151-bp HindIII fragment, which is deleted in both of the defective mitochondrial DNAs. Besides the previously identified gene for a methionine tRNA, the 2151-bp DNA sequence contains an open reading frame with the potential to code for a hydrophobic protein 583 amino acids long. This hydrophobic protein has three blocks of significant homology with proteins coded by URF2 found in other mitochondrial genomes. Since the mammalian mitochondrial URF2 has recently been shown to code for a subunit of NADH dehydrogenase, part of the DNA sequence missing in the E35 stopper mutant of N. crassa may also code for a subunit of NADH dehydrogenase.
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PMID:The E35 stopper mutant of Neurospora crassa: precise localization of deletion endpoints in mitochondrial DNA and evidence that the deleted DNA codes for a subunit of NADH dehydrogenase. 301 26

The site of synthesis of the iron-sulfur subunits of the flavoprotein and iron-protein fractions of the human respiratory chain NADH dehydrogenase has been investigated to test the possibility that any of them is synthesized in mitochondria. For this purpose, antibodies specific for individual subunits of the bovine enzyme, which cross-reacted with the homologous human subunits in immunoblot assays, were tested against HeLa cell mitochondrial proteins labeled in vivo with [35S]methionine in the absence or presence of inhibitors of mitochondrial or cytoplasmic protein synthesis. The results clearly indicated that all the iron-sulfur subunits of the flavoprotein and iron-protein fractions of human complex I are synthesized in the cytosol and are, therefore, encoded in nuclear genes.
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PMID:The site of synthesis of the iron-sulfur subunits of the flavoprotein and iron-protein fractions of human NADH dehydrogenase. 318 98

The nucleotide sequence of a 3849-bp fragment of starfish mitochondrial genome was determined. The genes for NADH dehydrogenase subunits 3, 4, 5, and COIII, and three kinds of (tRNA(UCNSer), tRNA(His), and tRNA(AGYSer) were identified by comparing with the genes of other animal mitochondria so far elucidated. The gene arrangement of starfish mitochondrial genome was different from those of vertebrate and insect mitochondrial genomes. Comparison of the protein-encoding nucleotide sequences of starfish mitochondria with those of other animal mitochondria suggested a unique genetic code in starfish mitochondrial genome; both AGA and AGG (arginine in the universal code) code for serine, AUA (isoleucine in the universal code but methionine in most mitochondrial systems) for isoleucine, and AAA (lysine) for asparagine. It was also inferred that these AGA and AGG codons are decoded by serine tRNA(AGYSer) originally corresponding to AGC and AGU codons. This situation is similar to the case of Drosophila mitochondrial genome. Variations in the use of AGA and AGG codons were discussed on the basis of the evolution of animals and decoding capacity of various tRNA(AGYSer) species possessing different sizes of the dihydrouridine (D) arm.
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PMID:Unusual genetic codes and a novel gene structure for tRNA(AGYSer) in starfish mitochondrial DNA. 367 36


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