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:4.1.1.49 (phosphoenolpyruvate carboxykinase)
4,654 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Xenopus laevis (Daudin) adult specimens were submitted to hypophysectomy. Although the operation resulted subtotal, it served the purpose of removing the prolactin-producing cells, whereby the involvement of endogenous prolactin in osmoregulation phenomena was excluded. In the operated animals treated with ovine prolactin the following metabolic parameters, which are closely dependent upon interrenal activity, were estimated: 1) intestine alkaline phosphomonoesterase activity (E.C. 3.1.3.1); 2) liver glycogen level; 3) glucose-6-phosphatase (E.C. 3.1.3.9.) and phosphoenolpyruvate carboxykinase (E.C. 4.1.1.32.) in the liver; 4) blood glucose level; 5) blood ammonia and urea levels; 6) carbamoylphosphate synthetase activity in the liver (E.C. 2.7.2.a); 7) muscle sodium and potassium levels. The above metabolic parameters were found to be pressed by subtotal hypophysectomy and after subsequent prolactin treatment showed the tendency to go back to values similar to those of control animals.
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PMID:Biochemical data on subtotally hypophysectomized Xenopus laevis (Daudin) adult specimens treated or not with prolactin. 21 25

This study describes the intracellular compartmentalization of three different mRNAs in the polarized rat fetal enterocyte. They encode proteins that are known to be localized within different regions of the epithelial cell namely (i) the apical, membrane-bound glycoprotein, lactase-phlorizin hydrolase (lactase), (ii) the mitochondrially localized enzyme, carbamoylphosphate synthetase (CPS), and (iii) the cytoplasmically localized enzyme, phosphoenolpyruvate carboxykinase (PEPCK). These mRNAs are found in close proximity to their respective protein products, i.e. the apical membrane, mitochondria and cytoplasm, respectively. The significance of these observations is twofold; (i) they indicate that mRNAs are sorted into specific domains of the cytosol of intestinal epithelial cells; and (ii) they imply the presence of two distinct pathways of mRNA targeting one that allows transport of mRNAs that are translated on ribosomes associated with the rough endoplasmic reticulum (lactase mRNA), and the other that allows sorting of mRNAs that are translated on free polysomes (CPS and PEPCK mRNA).
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PMID:Messenger RNA sorting in enterocytes. Co-localization with encoded proteins. 156 19

A hybridocytochemical analysis of adult liver from normal control and from hormonally and dietary-treated rats was carried out, using radioactively-labelled probes for the mRNAs of glutamine synthetase (GS), carbamoylphosphate synthetase (CPS) and phosphoenolpyruvate carboxykinase (PEPCK). In line with previous findings, GS mRNA is exclusively expressed in a small pericentral compartment, CPS mRNA exclusively in a contiguous large periportal compartment and PEPCK mRNA across the entire porto-central distance. The density of labelling in CPS and PEPCK mRNA-positive hepatocytes decreases in a porto-central direction. Starvation resulted in a reversal of the gradient of CPS mRNA within its periportal compartment; glucose refeeding counteracted this effect. Livers of glucocorticosteroid-treated, starved or diabetic rats also revealed a reversal of the normal gradient of CPS mRNA, but now across the entire porto-central distance. The patterns of expression of GS and PEPCK mRNA remained essentially unchanged, notwithstanding substantial changes in the levels of expression. It is concluded that blood-borne factors constitute the major determinants for the expression patterns of CPS mRNA within the context of the architecture of the liver lobulus.
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PMID:Diet- and hormone-induced reversal of the carbamoylphosphate synthetase mRNA gradient in the rat liver lobulus. 197 48

Glucocorticosteroid, thyroid hormones and cyclic AMP can induce the synthesis of carbamoylphosphate synthetase and phosphoenolpyruvate carboxykinase in cultures of hepatocytes as soon as these cells differentiate from the embryonic foregut. The low levels of both enzymes that can accumulate in such still protodifferentiated hepatocytes are due to low levels of enzyme synthesis. In cultures, the rate of synthesis of both enzymes increases continually in the presence of hormones, showing that maturation of the capacity for synthesis towards the postnatal, fully differentiated situation is occurring in these cells. The turnover rate of both enzymes in embryonic hepatocytes is lower in the presence of hormones than in the absence, but does not change during the culture period. In the presence of hormones the turnover rate is comparable to that found in adult rat liver in vivo. The development of the capacity to accumulate organ-specific enzymes in vitro (and hence the rate of enzyme synthesis) is found to be comparable to that in utero.
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PMID:Synthesis, accumulation and turnover of carbamoylphosphate synthetase and phosphoenolpyruvate carboxykinase in cultures of embryonic rat hepatocytes. 243 10

To gain insight into the mechanisms that govern the first steps of liver-specific enzyme accumulation upon hormone exposure, the initial accumulation of carbamoylphosphate synthetase, phosphoenolpyruvate carboxykinase, and arginase in monolayer cultures of Embryonic Day 14 rat hepatocytes was studied. By using different fluorescent labels the initial accumulation of two enzymes could be studied simultaneously in individual cells. Both microscopic and flow cytometric analyses showed that the initial expression of genes that are under the same hormonal control appears to lack the coordinated regulation of expression that is seen later in development. The coordination is gradually established during exposure to hormones. Once gene expression becomes coordinated, the enzyme content appears to increase continuously with time. Therefore, we postulate that within individual embryonic hepatocytes the initial intercellular heterogeneity in rate of accumulation of a particular protein may be the result of competition of different genes for an initially limiting supply of common regulatory factors, leading to random differences in the rate of accumulation of the respective gene products. This makes the initiation of liver-specific gene expression within the hepatocytes a stochastic event.
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PMID:The initiation of hepatocyte-specific gene expression within embryonic hepatocytes is a stochastic event. 247 86

The liver is the "glucostat" of the organism and serves at the same time as an "ammonia-sink and pH stat". The key enzymes involved in glucose uptake and release and in urea and glutamine formation are reciprocally distributed over the liver parenchyma: The glucogenic enzymes phosphoenolpyruvate carboxykinase (PEPCK), fructosebisphosphatase (FBPase) and glucose-6-phosphatase (G6Pase) as well as the ureagenic enzyme carbamoylphosphate synthetase (CAPS) are predominant in the periportal zone. The glycolytic enzymes glucokinase (GK) and pyruvate kinase type L (PKL) as well as the glutaminogenic enzyme glutamine synthetase (GluNS) are prevalent in the perivenous zone. This heterogeneity appears to be a prerequisite for the normal "glucostat, ammonia-sink and pH-stat" function of the liver. After birth the liver is a gluconeogenic organ, only with weaning it becomes a "glycolytic/gluconeogenic" glucostat. In the rat zonation of PEPCK, G6Pase and CAPS developed gradually after birth and was completed before weaning, i.e. before it would be functionally required. After 2/3 partial hepatectomy the liver looses its normal glucostat function and becomes a gluconeogenic organ. With this change the zonation of PEPCK and PKL were also lost; it was restored only during the second week after operation. During starvation the liver also looses its glucostat function to become the major glucose supplier of the organism. Zonation of PEPCK and PKL were diminished to such an extent that the major function of the perivenous zone was altered from glucose uptake to release. In diabetes the liver does not loose its glucostat function; however, the function is severely impaired. Zonation of PEPCK was increased and that of PKL decreased in such a manner that the major function of the perivenous zone, glucose uptake, was not entirely changed but only diminished. It can be concluded that in the various physiological states studied the zonation of enzymes correlated well with the glucostat function of the liver.
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PMID:Dynamics of zonal hepatocyte heterogeneity. Perinatal development and adaptive alterations during regeneration after partial hepatectomy, starvation and diabetes. 301 Mar 76

The aim of this study was to establish whether the initial accumulation of hepatocyte-specific proteins after hormone induction is regulated at the pretranslational and/or the translational level. To this end, mRNA molar concentrations were determined and compared with rates of protein synthesis from previous studies [van Roon, M.A., Charles, R. & Lamers, W.H. (1987) Eur. J. Biochem. 165, 229-234]. In vivo, carbamoylphosphate-synthetase mRNA starts to accumulate at day 17 of pregnancy. Phosphoenolpyruvate-carboxykinase mRNA starts to accumulate only just prior to birth. Embryonic day 14 (i.e. 8 days before the expected day of birth), livers were chosen to study the regulation of the initiation of hepatocyte-specific mRNA accumulation in vitro. Accumulation of carbamoylphosphate-synthetase and phosphoenolpyruvate-carboxykinase mRNA is regulated by the same hormones as accumulation of the respective proteins. The rate at which carbamoylphosphate-synthetase and phosphoenolpyruvate-carboxykinase mRNA molecules accumulate in cultured embryonic hepatocytes is relatively low, compared to that of postnatal hepatocytes. However, the increase of the rate of synthesis of carbamoylphosphate-synthetase and phosphoenolpyruvate-carboxykinase protein is even 3-6-fold slower than that of mRNA. This shows that initially mRNAs accumulate intracellularly to a relatively high concentration without being efficiently translated or translatable. Only after the mRNA concentration reaches a plateau of 72 h and 48 h respectively, the cellular capacity to synthesize the respective proteins increases. Therefore, the translational efficiency is certainly one of the major rate-limiting factors of the initial phases of expression of the hepatocyte-specific genes for carbamoylphosphate synthetase and phosphoenolpyruvate carboxykinase.
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PMID:Accumulation of carbamoylphosphate-synthetase and phosphoenolpyruvate-carboxykinase mRNA in embryonic rat hepatocytes. Evidence for translational control during the initial phases of hepatocyte-specific gene expression in vitro. 320 88

Chromosomal deletions at and around the albino locus on chromosome 7 of the mouse affect the enzyme activities and steady-state levels of mRNAs for five urea-cycle enzymes in liver. In newborn c3H homozygotes, activities of these enzymes were 43-62% of normal, while corresponding mRNA levels were 14-29% of normal. c14CoS deletion homozygotes expressed mRNA levels for these enzymes which were 32-48% of normal. However, transcription rates of these genes in hepatic nuclei of c3H/c3H mice were reduced only to 57-84% of normal. Since effects of the deletions had previously been noted in the kidney, mRNA levels for three enzymes expressed also in the kidney were examined. Mice homozygous for the c3H deletion, shown previously to have drastically reduced mRNA levels for phosphoenolpyruvate carboxykinase in the liver, expressed the same deficiency in the kidney, while mRNA levels for argininosuccinate synthetase and argininosuccinate lyase were reduced in the liver but remained unaffected in the kidney. However, mRNA levels for phosphoenolpyruvate carboxykinase, carbamyl phosphate synthetase I, and ornithine transcarbamylase were unaffected in the intestine of c3H homozygotes. The results suggest that a regulatory factor(s) encoded in the DNA encompassed by the deletion is involved in the normal developmental maturation of hepatocytes and certain cells in the kidney.
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PMID:Effects of deletions in mouse chromosome 7 on expression of genes encoding the urea-cycle enzymes and phosphoenolpyruvate carboxykinase (GTP) in liver, kidney, and intestine. 324 91

A completely defined medium (EHM-1), which reflects the amino acid composition of fetal rat serum and contains albumin as the sole proteinaceous compound, allows the accumulation of carbamoylphosphate synthetase and phosphoenolpyruvate carboxykinase in the presence of dexamethasone, dibutyryl cyclic AMP, and triiodothyronine to approximately twice the level attained in a standard culture medium (RPMI 1640) supplemented with 10% fetal bovine serum (and hormones). Using the EHM-1 medium we could show that the capacity of hepatocytes to synthesize phosphoenolpyruvate carboxykinase in the presence of hormones is manifest as soon as the cells differentiate from the embryonic foregut (embryonic Day 11). Furthermore we could show that embryonic hepatocytes can become binuclear or polyploid when cultured in the presence of thyroid hormone.
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PMID:Amino acid environment determines expression of carbamoylphosphate synthetase and phosphoenolpyruvate carboxykinase in embryonic rat hepatocytes. 406 99

The construction and cloning of a cDNA complementary to the mRNA of rat liver carbamoylphosphate synthetase (ammonia) is described. Using this cDNA, the size of the mature, cytosolic carbamoylphosphate synthetase (ammonia) mRNA is estimated to be 6.0 Kb. The levels of carbamoylphosphate synthetase (ammonia) mRNA in liver are shown to be regulated by glucocorticosteroids and cyclic AMP. By studying mRNA levels of carbamoylphosphate synthetase, albumin and phosphoenolpyruvate carboxykinase, using specific cDNA clones, we show that carbamoylphosphate synthetase gene expression, like that of albumin is liver-specific.
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PMID:Regulation of mRNA levels of rat liver carbamoylphosphate synthetase by glucocorticosteroids and cyclic AMP as estimated with a specific cDNA. 621 82


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