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:3.6.3.14 (ATP synthase)
7,042 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Palmitic acid and gramicidin D at low concentrations uncouple photophosphorylation in a mechanism that is inconsistent with classical uncoupling in the following properties: (1) delta pH, H+ uptake, or the transmembrane electric potential is not inhibited. (2) O2 evolution is stimulated under nonphosphorylating conditions but slightly inhibited in the presence of adenosine 5'-diphosphate + inorganic phosphate (Pi). (3) Light-triggered adenosine 5'-triphosphate (ATP)-Pi exchange is hardly affected, and ATPase activity is only slightly stimulated. (4) ATP-induced delta pH formation is selectively inhibited. This characteristic uncoupling is observed only when the native coupling sites of the electron transport system are used for energization such as for methylviologen-coupled phosphorylation. With pyocyanine, which creates an artificial coupling site, 1000-fold higher gramicidin D and higher palmitic acid concentrations are required for inhibition, and the inhibition is accompanied by a decrease in delta pH. Moreover, comparison between photosystem 1 and photosystem 2 electron transport and the effects of membrane unstacking suggest that low gramicidin D preferentially inhibits photosystem 2, while palmitic acid inhibits more effectively photosystem 1 coupling sites. The inhibitory capacity of fatty acids significantly drops when the chain length is reduced below 16 hydrocarbons or upon introduction of a single double bond in the hydrocarbon chain. It is suggested that palmitic acid and gramicidin D interfere with a direct H+ transfer between specific electron transport and the ATP synthase complexes, which provides an alternative coupling mechanism in parallel with bulk to bulk delta microH+. The sites of inhibition seem to be located in chloroplast ATP synthase, photosystem 2, and the cytochrome b6f complexes.
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PMID:Anomalous uncoupling of photophosphorylation by palmitic acid and by gramicidin D. 245 May 61

The structural organization of the entire human nuclear encoded gene for mitochondrial cytochrome c1 was determined by analyzing a clone obtained from an EMBL3 genomic DNA library. The gene spans 2.4-kilobase pairs and contains seven exons interrupted by six introns of relatively small sizes. All intron/exon splice junctions follow the GT/AG rule. The 5'-flanking region of the gene lacks typical transcriptional regulatory sequence elements such as TATA and CAAT boxes but contains seven putative GC boxes (Sp1 binding sites) and several sequences that resemble another type of the Sp1 responsive element, the enhancer core consensus sequence, the AP-1 responsive element, and the cAMP- and phorbol ester-inducible element. The region also contains a 15-nucleotide sequence highly homologous to the AP-4 consensus sequence and to those in the 5'-flanking regions of the genes for two enzymes associated with respiratory function, the beta subunit of human ATP synthase and chicken 5-aminolevulinate synthase. The presequence, which is essential for the transport of the cytochrome c1 precursor into mitochondria, is encoded in both the first and second exons, and the nucleotide sequence corresponding to the presequence is separated by the first intron. This is the first example of a leader sequence coding for a presequence clearly separated into two parts by an intron.
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PMID:Structural organization of the human mitochondrial cytochrome c1 gene. 253 65

We have analyzed how translocation intermediates of imported mitochondrial precursor proteins, which span contact sites, interact with the mitochondrial membranes. F1-ATPase subunit beta (F1 beta) was trapped at contact sites by importing it into Neurospora mitochondria in the presence of low levels of nucleoside triphosphates. This F1 beta translocation intermediate could be extracted from the membranes by treatment with protein denaturants such as alkaline pH or urea. By performing import at low temperatures, the ADP/ATP carrier was accumulated in contact sites of Neurospora mitochondria and cytochrome b2 in contact sites of yeast mitochondria. These translocation intermediates were also extractable from the membranes at alkaline pH. Thus, translocation of precursor proteins across mitochondrial membranes seems to occur through an environment which is accessible to aqueous perturbants. We propose that proteinaceous structures are essential components of a translocation apparatus present in contact sites.
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PMID:Mitochondrial precursor proteins are imported through a hydrophilic membrane environment. 289 6

The in vitro effects of piperine on three bioenergetic reactions namely, oxidative phosphorylation, ATPase activity and calcium transport by isolated rat liver mitochondria have been investigated. Piperine was found to inhibit state 3 and DNP-stimulated respiration by mitochondria respiring with glutamate plus malate or succinate as substrates. The I50 values of piperine on oxidative phosphorylation in the presence of glutamate plus malate and succinate were 22 and 12 micrograms/mg mitochondrial protein respectively. With HTM preparations, the oxidation of added NADH and succinate was depressed by piperine while ascorbate plus TMPD oxidation was slightly affected. Piperine did not inhibit the mitochondrial ATPase activity induced by DNP, but by itself exerted stimulating activity on this enzyme. Piperine was also found to diminish calcium uptake and to facilitate the release of accumulated calcium by the mitochondria incubated with succinate or ATP. These results suggest that piperine inhibits mitochondrial oxidative phosphorylation at the level of respiratory chain, and the inhibitory site(s) is in the segment(s) ahead of cytochrome C. The mechanism of the piperine-induced ATPase activity is not known; but the effect of piperine on calcium transport is likely to be consequential to the effects of this compound on the mitochondrial respiratory chain and ATPase activity.
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PMID:Effects of piperine on bioenergetic functions of isolated rat liver mitochondria. 296 41

The genes for the following proteins were localized by hybridization analysis on the cyanelle genome of Cyanophora paradoxa: the alpha and beta subunits of phycocyanin (cpcA and cpcB); the alpha and beta subunits of allophycocyanin (apcA and apcB); the large and small subunits of ribulose-1,5-bisphosphate carboxylase (rbcL and rbcS); the two putative chlorophyll alpha-binding apoproteins of the photosystem I-P700 complex (psaA and psaB); four apoproteins believed to be components of the photosystem II core complex (psbA, psbB, psbC, and psbD); the two apoprotein subunits of cytochrome b-559 which is also found in the core complex of photosystem II (psbE and psbF); three subunits of the ATP synthase complex (atpA and atpBE); and the cytochrome f apoprotein (petA). Eighty-five percent of the genome was cloned as BamHI, BglII, or PstI fragments. These cloned fragments were used to construct a physical map of the cyanelle genome and to localize more precisely some of the genes listed above. The genes for phycocyanin and allophycocyanin were not clustered and were separated by about 25 kilobases. Although the rbcL gene was adjacent to the atpBE genes and the psbC and psbD genes were adjacent, the arrangement of other genes encoding various polypeptide subunits of protein complexes involved in photosynthetic functions was dissimilar to that observed for known chloroplast genomes. These results are consistent with the independent development of this cyanelle from a cyanobacterial endosymbiont.
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PMID:Gene map for the Cyanophora paradoxa cyanelle genome. 393 27

Submitochondrial particles prepared from liver and skeletal muscle of control and iron-deficient rats were examined for cytochrome content and for both energy-independent and energy-conserving functions. Liver submitochondrial particles appear quite resistant to iron deficiency with cytochrome content and electron-transferring or energy-conserving functions maintained at a level of 85% or better of normal. Iron-deficient skeletal muscle submitochondrial particles, in contrast, have decreased cytochrome content and only 15-20% of the normal capacity for oxidation through either complex I (NADH dehydrogenase) or complex II (succinate dehydrogenase). Energy-linked reactions which involve substrate oxidation/reduction (succinate----NAD+ reversed electron flow and succinate-driven energy-dependent transhydrogenation) are likewise markedly decreased, while ATP-driven energy-dependent transhydrogenation and mitochondrial ATPase are normal. Our data support the concept that iron deficiency leads to decreased electron-carrying capacity of iron-containing mitochondrial enzymes, with skeletal muscle being much more susceptible than liver, but that the mitochondria are otherwise normal with regard to energy conservation.
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PMID:Effect of iron deficiency on energy conservation in rat liver and skeletal muscle submitochondrial particles. 405 63

The contents of mitochondrial inner membrane protein complexes were compared in normal liver and in Zajdela hepatoma mitochondria by the immunotransfer technique. Antibodies against core proteins 1 and 2, cytochrome c1, the iron-sulfur protein of Complex III, subunits I and II of cytochrome oxidase, and the alpha and beta subunits of the F1-ATPase were used. In addition, antibodies against a primary dehydrogenase, beta-hydroxybutyrate dehydrogenase, as well as the outer membrane pore protein were used. The results indicate that the components of the cytochrome chain and porin are greatly enriched in hepatoma mitochondria compared to normal rat liver mitochondria. This enrichment was also reflected in the rates of respiration in tumor mitochondria using a variety of substrates. Enrichment of porin may partially account for increased hexokinase binding to tumor mitochondria. In contrast to the respiratory chain components, the F1-ATPase and F0 (measured by DCCD binding) were not increased in tumor mitochondria. Thus, Zajdela hepatoma mitochondria components are nonstoichiometric, being enriched in oxidative capacity but relatively deficient in ATP synthesizing capacity. Finally, beta-hydroxybutyrate dehydrogenase, which is often decreased in hepatoma mitochondria, was shown here by immunological methods to be decreased by only 40%, whereas enzyme activity was less than 5% of that in normal rat liver.
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PMID:Immunochemical analysis of the membrane proteins of rat liver and Zajdela hepatoma mitochondria. 609 64

A newborn female, the second child of consanguineous parents, exhibited general muscle hypotonia, apathy, hepatomegaly and failure to thrive from birth and signs of craniofacial dysmorphia were present. Pipecolic and trihydroxicoprostanoic acid were excreted in the urine and serum transferrin, ferritin and iron were markedly elevated. At the age of 7 weeks the baby died of respiratory insufficiency. Besides malformations of the brain, renal cysts, liver damage with hypoplastic intrahepatic bile ducts and cholestasis, increased storage of iron and cytochemically proven deficiency of peroxisomes in liver and kidney, morphological studied provided evidence of a mitochondrial myopathy in striated muscle with the accumulation of enlarged bizarre mitochondria, showing only minor structural abnormalities. No defects of NADH-reductase, succinate-dehydrogenase or cytochrome-c-oxidase were demonstrated histochemically. Cytochemical-ultrastructural investigation of mitochondrial ATPase revealed activation of the ATP-synthesising enzyme even before the addition of an uncoupler, this indicating loosely coupled oxidative phosphorylation. In addition a high rate of subcellular autophagy with segregation of mitochondria and focal loss of fibrils was present. Muscle damage in Zellweger syndrome appears to be the consequence of complex, interacting metabolic processes. The mitochondrial myopathy thereby induced allows a better understanding of general muscle hypotonia, one of the leading symptoms of this disorder.
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PMID:Mitochondrial myopathy with loosely coupled oxidative phosphorylation in a case of Zellweger syndrome. A cytochemical-ultrastructural study. 614 41

1. Mitochondrial translation products of yeast Saccharomyces cerevisiae were separated according to charge as well as molecular weight by a highly resolving two dimensional electorphoretic technique (isoelectric focusing in the first dimension ana SDS-electrophoresis in the second dimension). 2. The major protein components (the oligomeric form of subunit 9 of mitochondrial ATPase, var 1, cytochrome oxidase subunits I, II and III, subunit 6 of mitochondrial ATPase and cytochrome b apoprotein) were identified either from their mobility in SDS-electrophoresis or by using mit- mutants defective in certain mitochondrially made polypeptides. 3. This method allowed the separation of subunit III of cytochrome oxidase and subunit 6 of mitochondrial ATPase which cannot be resolved by conventional SDS-polyacrylamide gel electrophoresis. 4. Subunit II of cytochrome oxiodase resolves in two spots of similar pI values and subunit 6 of mitochondrial ATPase resolves in two spots of similar molecular weight. In both cases the double spots disappear simultaneously following a single mutation in the coresponding structural gene. 5. Total mitochondrial proteins were also resolved two-dimensionally revealing over 100 components. The mitochondrial translation products, with the exception of subunit 9 of mitochondrial ATPase, could be easily recognized among the other mitochondrial proteins.
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PMID:Biogenesis of mitochondria. Two-dimensional electrophoretic analysis of mitochondrial translation products in yeast. 625 Jun 20

Rats malnourished since birth and fed on a protein-free diet for 2 weeks showed a 23-27% decrease in the State-3 oxidation of glutamate, succinate and ascorbate + NNN' N'-tetramethyl-p-phenylenediamine by liver mitochondria compared with control fed animals. ATP synthesis and the respiratory control index were diminished at the three coupling sites, but significant alterations were not observed in ADP/O ratios. Vmax. for NADH oxidation in electron-transport particles was 40% lower. Mitochondrial cytochromes b and c1 remained unchanged, but cytochrome c was increased by 26%. Cytochromes a + a3 were diminished by 22%. Vmax. for mitochondrial ATPase was 23% lower. These results suggest that the lower content of cytochrome a + a3 at the rate-controlling step of oxidative phosphorylation in malnourished rats might be mainly responsible for the decrease in substrate oxidations as well as ATP synthesis at the three coupling sites. The decreased synthesis and hydrolysis of ATP suggests that other energy-dependent mitochondrial processes could be decreased during malnutrition.
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PMID:Nutritional effects on mitochondrial bioenergetics. Alterations in oxidative phosphorylation by rat liver mitochondria. 671 14


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