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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The purpose of this study was to elucidate the effects of aging on diaphragmatic mitochondrial function. Diaphragm mitochondria were prepared from specific pathogen-free rats aged 7 wk (n = 7), 35 wk (n = 7), and 55 wk (n = 7). The activities of various portions of the mitochondrial electron transport chain, i.e., complexes I, II, III, and IV, were measured enzymatically. The specific activities of complex I decreased significantly (P less than 0.01) in 35-wk-old rats (726 +/- 90 nmol/min/mg protein) compared with 7-wk-old rats (1,018 +/- 121), and the decrease was more remarkable in 35-wk-old rats (565 +/- 64; P less than 0.01 versus 35-wk-old). The activities of complex IV also decreased significantly (P less than 0.01) in 55-wk-old rats (1,222 +/- 191) compared with 7-wk-old rats (1,797 +/- 208); however, no significant changes in complex IV activities between 7-wk-old rat and 35-wk-old rats were observed. In contrast, the activities of complex II and III were not affected by aging. Limb muscle, heart, and liver mitochondria were also prepared from the same rats. The same tendency was observed in limb muscle mitochondria; however, in heart and liver mitochondria, activities of all four complexes were not changed in rats of all age groups. These results indicate that vulnerability of mitochondrial electron transport chain to aging differs from organ to organ and that it also differs from portion to portion in the electron transport chain and the most vulnerable site was complex I.(ABSTRACT TRUNCATED AT 250 WORDS)
Am J Respir Cell Mol Biol 1992 Jan
PMID:Age-related decrease in respiratory muscle mitochondrial function in rats. 172

Biochemical studies on the male reproductive tissues and seminal secretions have been made with reference to sperm metabolism and different stages of maturity in the crab Scylla serrata. The results reveal that the seminal plasma and spermatophores are rich in protein, carbohydrate, and lipid. In general, organic components of spermatophores are considerably higher than those of seminal plasma. Enzyme studies show that the succinate dehydrogenase (SDH) activity is very low, whereas fumarate reductase (FR) and lactate dehydrogenase (LDH) exhibit high activity. Electrophoretic studies on LDH show that, in addition to the occurrence of a sperm-specific fraction, LDHx, the M-type subunits are predominant in the mature spermatophores. These results from enzyme studies suggest that sperm metabolism is mainly anaerobic, utilizing the carbohydrates as substrates. The results for maturational changes reveal that the male reproductive tissues and their secretions contain lesser quantity of organic components in the immature crabs; as the maturity proceeds, there is not only concentration of organic substances but also an increase in the size of spermatophores. The concentration of biochemical constituents is highest in the proximal vas deferens (PVD), suggesting that the granular seminal plasma as well as the sperm-agglutinating substance and spermatophoric wall are secreted in this region. The spermatheca of the unmated female crabs are poor in organic constituents. After mating, their contents are enriched by organic substances derived from contributions of the seminal substances. During sperm storage in the spermatheca, only the carbohydrates decline steeply. A low activity of SDH, but a moderate level of LDH and a high level of FR activity, is recorded in the spermathecal content of mated crabs, providing further evidence for anaerobic metabolism of sperm during storage in female. A sharp fall in the stored carbohydrates constitutes further evidence in this regard.
Mol Reprod Dev 1991 Sep
PMID:Biochemistry of seminal secretions of the crab Scylla serrata with reference to sperm metabolism and storage in the female. 178 87

The 78-kDa glucose-regulated protein (GRP78) is ubiquitously expressed in many cell types. Its promoter contains multiple protein-binding sites and functional elements. In this study we examined a high affinity protein-binding site spanning bp -198 to -180 of the rat grp78 promoter, using nuclear extracts from both B-lymphoid and HeLa cells. This region contains a sequence TGACGTGA which, with the exception of one base, is identical to the cAMP-response element (CRE). Site-directed mutagenesis reveals that this sequence functions as a major basal level regulatory element in hamster fibroblast cells and is also necessary to maintain high promoter activity under stress-induced conditions. By gel mobility shift analysis, we detect two specific protein complexes. The major specific complex I, while immunologically distinct from the 42-kDa CRE-binding protein (CREB), binds most strongly to the grp site, but also exhibits affinity for the CRE consensus sequence. As such, complex I may consist of other members of the CREB/activating transcription factor protein family. The minor specific complex II consists of CREB or a protein antigenically related to it. A nonspecific complex III consists of the Ku autoantigen, an abundant 70- to 80-kDa protein complex in HeLa nuclear extracts. By cotransfection experiments, we demonstrate that in F9 teratocarcinoma cells, the grp78 promoter can be transactivated by the phosphorylated CREB or when the CREB-transfected cells are treated with the calcium ionophore A23187. The differential regulation of the grp78 gene by cAMP in specific cell types and tissues is discussed.
Mol Endocrinol 1991 Dec
PMID:A binding site for the cyclic adenosine 3',5'-monophosphate-response element-binding protein as a regulatory element in the grp78 promoter. 183 91

A rapid switch from a fermentative to a primarily oxidative type of glucose utilization was observed during in vitro differentiation of Trypanosoma brucei STIB348 and EATRO1244 bloodstream to procyclic trypomastigotes. In accordance with previously published reports bloodstream populations produced pyruvate as the major end product of glucose catabolism, together with very small amounts of CO2, succinate and glycerol. During differentiation pyruvate excretion decreased within 48 h to the low levels produced by 28-day procyclic stages. Concomitant with the decline in pyruvate formation, acetate appeared as a new product and the rates of respiratory CO2 increased considerably. The amount of carbon released with these compounds could account for nearly all of the glucose carbon consumed. Rates of glucose utilization and formation of acetate and CO2 in cells differentiated for 48 h were essentially the same as those found in 28-day procyclics. Succinate and glycerol excretion remained low during the entire transformation process, and no significant difference in the pattern and quantities of end products were found between the two trypanosome strains. During trypanosome differentiation the changes in metabolism were associated with marked alterations in enzyme activity levels. Activities of the tricarboxylic acid (TCA) cycle enzymes citrate synthase, isocitrate dehydrogenase (NAD+), succinate dehydrogenase and fumarase were not detectable in bloodstream trypomastigotes but appeared upon differentiation for 24 h. An exception was citrate synthase whose activity was not demonstrable until 48 h postinoculation into culture. After 48 h the majority of the TCA cycle enzyme activities continued to increase steadily until day 28. Pyruvate kinase activity decreased in differentiating cells after 48 h to about 25% of the level found in bloodstream trypomastigotes.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Biochem Parasitol 1991 Mar
PMID:Alterations in Krebs cycle enzyme activities and carbohydrate catabolism in two strains of Trypanosoma brucei during in vitro differentiation of their bloodstream to procyclic stages. 190 88

The uptake of L-[14C]glycine and the activities of intracellular marker enzymes of enterocytes were studied in ligated small intestinal segments of rabbits during experimental cholera induced by intra-intestinal injection of pure cholera toxin (CT). No significant difference was observed in the active uptake of L-[14C]glycine between the CT-injected small intestinal segments and the saline-injected control segments, indicating that there is an intact active transport system for intestinal absorption of L-[14C]glycine during experimental cholera in rabbits. Apart from a significant increase in the activity of a brush border marker enzyme (alkaline phosphatase), there was no significant difference between the activities of marker enzymes for lysosomes (acid phosphate), microsomes (glucose-6-phosphatase), mitochondria (succinate dehydrogenase), and a cytosol enzyme (proteinase) in mucosal homogenates of CT-injected small intestinal segments compared to controls. The finding of an intact mitochondrial marker enzyme together with intact L-[14C]glycine absorption provides a scientific basis for considering the use of glycine and other monoamino monocarboxylic amino acids in "improved" oral rehydration solutions for the treatment of acute diarrhea, including cholera.
Mol Biol Med 1991 Feb
PMID:Effect of cholera toxin on L-[14C]glycine uptake and intestinal cell enzymes in rabbit. 194 84

The transcription of the polycistronic puf operon which encodes pigment binding proteins of the reaction center and light-harvesting complex I of Rhodobacter capsulatus is regulated by the oxygen tension in the culture. A DNA sequence upstream of the puf transcriptional start was identified as a protein binding site. A DNA fragment carrying this DNA sequence participated in the formation of two DNA-protein complexes. The relative amounts of the two complexes were dependent on the oxygen tension in cultures from which the cytosolic fraction used for the in vitro binding studies was isolated. A single base pair transition within the protein binding site affected the oxygen-dependent expression of puf in vivo and the formation of DNA-protein complexes in vitro. The data suggest that the formation of specific DNA-protein complexes is involved in the oxygen-dependent regulation of the puf promoter. A DNA fragment containing the promoter region of the puc operon that encodes proteins of the light-harvesting complex II acted as a competitor for the formation of the DNA-protein complexes with the puf-specific fragment, indicating coregulation of the two operons.
Mol Gen Genet 1991 Apr
PMID:A DNA sequence upstream of the puf operon of Rhodobacter capsulatus is involved in its oxygen-dependent regulation and functions as a protein binding site. 203 11

In this paper we have examined the effect of cold exposure on hepatic mitochondrial state 3 respiration and ATP synthesis, using succinate as the substrate, in euthyroid, hypothyroid and hyperthyroid rats. The results show that cold exposure does not elicit any variation in the above parameters in euthyroid and hyperthyroid rats, whereas when hypothyroid rats are exposed to cold, a significant increase (about +45%) occurs in state 3 respiration and ATP synthesis. We have also measured succinic dehydrogenase specific activity and uncoupled respiration during cold exposure in various thyroid states. The finding that cold exposure elicits no variation in the above parameters indicates that there is some control on ATP synthase and/or adenine nucleotide translocator. The above findings, as a whole, suggest that cold exposure acts on oxidative phosphorylation only if triiodothyronine is lacking, by controlling ATP synthase and/or adenine nucleotide translocator.
Mol Cell Endocrinol 1991 Jan
PMID:The effect of thyroid state and cold exposure on rat liver oxidative phosphorylation. 205 Feb 63

The neurochemical changes induced by malathion, an organophosphate compound, were determined in rats. Maximal changes were found in the brain 2 h after the administration of malathion in a dose of 500 mg/kg ip. The activities of cholinesterase and succinic dehydrogenase were reduced whereas those of glycogen phosphorylase, phosphoglucomutase, and hexokinase were increased; the lactate content of brain was also increase. In malathion treated adrenalectomized animals, changes in the activities of cerebral cholinesterase and succinic dehydrogenase were still present; other changes were, however, abolished by adrenalectomy. Activities of certain enzymes, glucose-6-phosphatase, glucose-6-phosphate dehydrogenase, and lactate dehydrogenase were not significantly altered by malathion in normal or adrenalectomized animals. The results indicate that cerebral cholinergic mechanism in malathion treated animals was not modified by adrenalectomy which, however, abolished or reduced changes in the activities of certain glycolytic and glycogenolytic enzymes that are involved in the utilization or metabolism of glucose. The brain lactate content in malathion treated adrenalectomized animals was, also, not significantly different from the control values, suggesting that modification of induced changes by adrenalectomy.
Mol Chem Neuropathol
PMID:Modification of malathion induced neurochemical changes by adrenalectomy in rats. 209 80

In HeLa cells, RNA polymerase III (pol III)-mediated transcription is severely inhibited by poliovirus infection. This inhibition is due primarily to the reduction in transcriptional activity of the pol III transcription factor TFIIIC in poliovirus-infected cells. However, the specific binding of TFIIIC to the VAI gene B-box sequence, as assayed by DNase I footprinting, is not altered by poliovirus infection. We have used gel retardation analysis to analyze TFIIIC-DNA complexes formed in nuclear extracts prepared from mock- and poliovirus-infected cells. In mock-infected cell extracts, two closely migrating TFIIIC-containing complexes, complexes I and II, were detected in the gel retardation assay. The slower migrating complex, complex I, was absent in poliovirus-infected cell extracts, and an increase occurred in the intensity of the faster-migrating complex (complex II). Also, in poliovirus-infected cell extracts, a new, rapidly migrating complex, complex III, was formed. Complex III may have been the result of limited proteolysis of complex I or II. These changes in TFIIIC-containing complexes in poliovirus-infected cell extracts correlated kinetically with the decrease in TFIIIC transcriptional activity. Complexes I, II, and III were chromatographically separated; only complex I was transcriptionally active and specifically restored pol III transcription when added to poliovirus-infected cell extracts. Acid phosphatase treatment partially converted complex I to complex II but did not affect the binding of complex II or III. Dephosphorylation and limited proteolysis of TFIIIC are discussed as possible mechanisms for the inhibition of pol III-mediated transcription by poliovirus.
Mol Cell Biol 1990 Oct
PMID:A transcriptionally active form of TFIIIC is modified in poliovirus-infected HeLa cells. 220 7

The fumarate reductase operon of Wolinella succinogenes is made up of three structural genes (frd-CAB). The frdC gene was located next to the promoter region and identified as the cytochrome b structural gene encoding 256 amino acid residues. The N-terminal amino acid sequences of seven fragments derived from the cytochrome b moiety of the enzyme all mapped within the frdC gene. This suggested that the enzyme contained only one species of cytochrome b. Re-evaluation of earlier measurements of subunit composition, haem B content and molecular weight led to the conclusion that the enzyme contained one molecule of cytochrome b with two haem B groups. The hydropathy plot of the amino acid sequence predicted five membrane-spanning hydrophobic segments, the first four of which contained a single histidine residue each. These residues could form the axial ligands to the two haem B groups. FrdC was found to be homologous with the cytochrome b (SdhC) of the Bacillus subtilis succinate dehydrogenase, but not with the hydrophobic subunits of the fumarate reductase or succinate dehydrogenase of Escherichia coli.
Mol Microbiol 1990 May
PMID:Wolinella succinogenes fumarate reductase contains a dihaem cytochrome b. 238 63


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