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

The C4 isoform of phosphoenolpyruvate carboxylase (PEPCase) in Flaveria trinervia is encoded by the ppcA subgroup of the PEPCase gene family and is abundantly expressed in the mesophyll cells of leaves. The homologous ppcA genes in the C3 plant F pringlei are only weakly expressed and their transcripts do not show the strictly leaf-specific accumulation pattern observed for the F. trinervia genes. Two representative members of the ppcA subfamilies of F. trinervia (C4) and F. pringeli (C3)-named ppcA1-were characterized by Southern blotting, nucleotide sequencing and primer extension analysis. Comparison of the deduced amino acid sequences reveals a close similarity between C4 and C3 isoforms. Only few C4-specific positions can be detected when all known plant PEPCases are included in the comparison. A regulatory domain involved in light-dependent phosphorylation/dephosphorylation of the C4 and crassulacean acid metabolism (CAM) isoforms is present in the ppcA1 gene products of both the C3 and C4 Flaveria. The 5' flanking regions are essentially homologous. The putative promoter regions share several identical sequence motifs (CCAAT, AT-1 and GT-1 box III/III* elements). Additionally, alterations in elements that could contribute to differences in expression rates and light regulation are found. The significance of these findings is discussed with respect to the molecular evolution of C4 photosynthesis in Flaveria.
Mol Gen Genet 1992 Aug
PMID:Homologous genes for the C4 isoform of phosphoenolpyruvate carboxylase in a C3 and a C4 Flaveria species. 150 52

The cytosolic phosphoenolpyruvate carboxykinase (PEPCK) gene is expressed in multiple tissues and is regulated in a complex tissue-specific manner. To map the cis-acting DNA elements that direct this tissue-specific expression, we made transgenic mice containing truncated PEPCK-human growth hormone (hGH) fusion genes. The transgenes contained PEPCK promoter fragments with 5' endpoints at -2088, -888, -600, -402, and -207 bp, while the 3' endpoint was at +69 bp. Immunohistochemical analysis showed that the -2088 transgene was expressed in the correct cell types (hepatocytes, proximal tubular epithelium of the kidney, villar epithelium of the small intestine, epithelium of the colon, smooth muscle of the vagina and lungs, ductal epithelium of the sublingual gland, and white and brown adipocytes). Solution hybridization of hGH mRNA expressed from the transgenes indicated that white and brown fat-specific elements are located distally (-2088 to -888 bp) and that liver-, gut-, and kidney-specific elements are located proximally (-600 to +69 bp). However, elements outside of the region tested are necessary for the correct developmental pattern and level of PEPCK expression in kidney. Both the -2088 and -402 transgenes responded in a tissue-specific manner to dietary stimuli, and the -2088 transgene responded to glucocorticoid stimuli. Thus, different tissues utilize distinct cell-specific cis-acting elements to direct and regulate the PEPCK gene.
Mol Cell Biol 1992 Mar
PMID:Tissue-specific, developmental, hormonal, and dietary regulation of rat phosphoenolpyruvate carboxykinase-human growth hormone fusion genes in transgenic mice. 154 85

The selective expression of a unique copy gene in several mammalian tissues has been approached by studying the regulatory sequences needed to control expression of the rat phosphoenolpyruvate carboxykinase (PEPCK) gene in transgenic mice. A transgene containing the entire PEPCK gene, including 2.2 kb of the 5'-flanking region and 0.5 kb of the 3'-flanking region, exhibits tissue-specific expression in the liver, kidney, and adipose tissue, as well as the hormonal and developmental regulation inherent to endogenous gene expression. Deletions of the 5'-flanking region of the gene have shown the need for sequences downstream of position -540 of the PEPCK gene for expression in the liver and sequences downstream of position -362 for expression in the kidney. Additional sequences upstream of position -540 (up to -2200) are required for expression in adipose tissue. In addition, the region containing the glucocorticoid-responsive elements of the gene used by the kidney was identified. This same sequence was found to be needed specifically for developmental regulation of gene expression in the kidney and, together with upstream sequences, in the intestine. The apparently distinct sequence requirements in the various tissues indicate that the tissues use different mechanisms for expression of the same gene.
Mol Cell Biol 1992 Mar
PMID:Differential regulation of the rat phosphoenolpyruvate carboxykinase gene expression in several tissues of transgenic mice. 154 20

When gel shift assays were performed with maize nuclear extract and a DNA fragment containing the cauliflower mosaic virus (CaMV) 35S promoter, three DNA-protein complexes were observed. Analyses with nuclear extracts prepared from green leaves, etiolated leaves, stems and roots showed that the complexes resulted from the existence of at least two nuclear factors. One of them is presumably a constitutive nuclear factor found in all tissues tested, and another is a leaf-specific factor present both in green and etiolated leaves. This leaf-specific nuclear factor seemed to be identical to MNF1, previously identified as a factor interacting with the promoter of the maize gene for phosphoenolpyruvate carboxylase involved in the C4 photosynthesis. Deletion analysis revealed that MNF1 binds to the sequence from -281 to -235 relative to the transcription start site of the CaMV 35S promoter. MNF1-like nuclear protein was also found in tobacco nuclear extracts. The possibility that MNF1 participates as a positive trans-acting factor in the expression of genes in maize leaves is discussed.
Plant Mol Biol 1992 Jul
PMID:MNF1, a leaf tissue-specific DNA-binding protein of maize, interacts with the cauliflower mosaic virus 35S promoter as well as the C4 photosynthetic phosphoenolpyruvate carboxylase gene promoter. 162 69

Insulin stimulates transcription and cytoplasmic accumulation of a specific mRNA (termed p33), while inhibiting transcription and accumulation of phosphoenolpyruvate carboxykinase (PEPCK) mRNA in rat H4IIE (H4) hepatoma cells. The present work examines the role of protein synthesis in regulation of these genes by insulin and dexamethasone. Like insulin, cycloheximide and anisomycin, two protein synthesis inhibitors, induced p33 transcription and reduced PEPCK transcription. The combination of either protein synthesis inhibitor and insulin did not induce p33 transcription or inhibit PEPCK transcription beyond that observed with either protein synthesis inhibitor alone. Dexamethasone induced both p33 and PEPCK transcription. The combination of insulin and dexamethasone, or protein synthesis inhibitors and dexamethasone, abolished dexamethasone-induced PEPCK transcription. Thus, protein synthesis inhibitors regulate transcription of the p33 and the PEPCK genes in an insulin-like manner.
Mol Cell Endocrinol 1992 Mar
PMID:Protein synthesis and insulin regulation of p33 and PEPCK gene expression. 163 18

Transcription of the gene for phosphoenolpyruvate carboxykinase is regulated by several hormones which control the level of glucose synthesis in vertebrate animals. A 490 bp segment located at the 5' end of the structural gene contains the necessary regulatory elements to account for the pattern of transcriptional regulation characteristic of the phosphoenolpyruvate carboxykinase gene. Multiple cis binding sites within the promoter and nuclear binding proteins have been identified and shown to play a role in the regulation of gene transcription. The interaction of these transcription factors with each other and with the phosphoenolpyruvate carboxykinase promoter is central to the regulated expression of this gene. The key role of cAMP and insulin in controlling the level of gene transcription will be discussed and related to the function of transcription factors currently known to regulate the tissue specific expression of the phosphoenolpyruvate carboxykinase gene.
Mol Cell Biochem
PMID:Regulation of phosphoenolpyruvate carboxykinase (GTP) gene transcription. 165 99

The ability of a retinoic acid (RA) response element (RARE) in the phosphoenolpyruvate carboxykinase (PEPCK) gene promoter to mediate effects of either RA or thyroid hormone (T3) on gene expression was studied. Fusion gene constructs consisting of PEPCK promoter sequences ligated to the chloramphenicol acetyltransferase (CAT) reporter gene were used for this analysis. While T3 induced CAT expression to a small degree (about twofold) when such constructs were transiently transfected into H4IIE rat hepatoma cells, along with an expression vector encoding the alpha subtype of the T3 receptor (TR), this effect was mediated by promoter sequences distinct from the PEPCK RARE. Although TRs were capable of binding the PEPCK RARE in the form of putative monomers, dimers, and heterodimers with RA receptors (RARs), this element failed to mediate any positive effect of T3 on gene expression. In contrast, the PEPCK RARE mediated six- to eightfold induction of CAT expression by RA. When TRs were coexpressed along with RARs in transfected H4IIE cells, this RA induction was substantially blunted in a T3-independent manner. This inhibitory effect may be due to the binding of nonfunctional TRs or TR-RAR heterodimers to the PEPCK RARE. A model is proposed to explain the previously observed in vivo effects of T3 on PEPCK gene expression.
Mol Cell Biol 1991 Oct
PMID:Specificity of a retinoic acid response element in the phosphoenolpyruvate carboxykinase gene promoter: consequences of both retinoic acid and thyroid hormone receptor binding. 194 93

The ability of an inositol phosphate-glycan (IPG) to mimic the effects of insulin on regulation of the expression of specific mRNAs was studied in isolated hepatocytes from normal and diabetic rats. Incubation of normal liver cells with IPG (10 microM) during 90 min produced a 5-fold decrease in phosphoenolpyruvate carboxykinase (PEPCK) mRNA levels, which had been previously increased about 10-fold by incubation with 8-bromo-cAMP (0.1 mM). The effect of IPG was dose dependent and could not be reproduced by galactose, glucosamine, or myo-inositol. IPG reduction of PEPCK mRNA is primarily due to a decrease in the rate of transcription of the gene, as judged by nuclear run-on transcription experiments performed in rat hepatoma H4IIE cells. In hepatocytes isolated from diabetic rats, treatment with 5 microM IPG for 15 min caused a 4-fold induction in the expression of alpha 2-microglobulin mRNA concomitantly with a 2.5-fold decrease in the level of PEPCK mRNA. Cleavage of IPG with nitrous acid abolished both the increase and the decrease in specific mRNAs levels. Glycosyl-phosphatidylinositol, the lipid precursor of IPG, did not modify either PEPCK or alpha 2-microglobulin mRNA levels. These data indicate that both positive and negative effects of insulin on the regulation of gene expression are mimicked by IPG.
Mol Endocrinol 1991 Aug
PMID:Insulin-like effects of inositol phosphate-glycan on messenger RNA expression in rat hepatocytes. 171 85

We have cloned and sequenced the pckA gene of Rhizobium sp. NGR234, a broad host-range strain. The gene encodes phosphoenolpyruvate carboxykinase (PEPCK), a key enzyme of gluconeogenesis. The locus was isolated and subcloned from a genomic library of NGR234 employing hybridization with an R. meliloti pck gene probe and complementation of a Tn5 mutant in this species. The DNA sequence of pckA (NGR234) was determined and encoded a PEPCK protein of 535 amino acids with a molecular weight of 58.4 kDa. The deduced polypeptide sequence was compared to those of three known ATP-dependent PEPCKs. Slightly higher homology was observed with yeast and trypanosome polypeptides than with that of Escherichia coli. We have identified several regions that are conserved in all four PEPCK proteins. A mutant constructed in the pck gene by site-directed mutagenesis with interposon omega failed to grow on succinate, malate and arabinose but grew on glucose and glycerol as sole carbon sources. These data show that NGR234 requires PEPCK-driven gluconeogenesis to grow on TCA cycle intermediates. A host-dependent effect of the pckA mutation was observed on nodule development and nitrogen fixation. Nodules formed by the site-directed mutant on Leucaena leucocephala and Macroptilium atropurpureum were FixRed, but on Vigna unguiculata were Fix-. The expression of the gene was positively regulated in free-living cells of NGR234 by either succinate or host-plant exudates, and was subject to catabolite repression by glucose.
Mol Gen Genet 1991 Nov
PMID:Site-directed mutagenesis and DNA sequence of pckA of Rhizobium NGR234, encoding phosphoenolpyruvate carboxykinase: gluconeogenesis and host-dependent symbiotic phenotype. 172 Aug 62

Biochemical and metabolic data have led to the conclusion that the enzyme phosphoenolpyruvate carboxykinase (PEPCK; EC 4.1.1.32) contributes to a critical point of divergence in energy conservation pathways between mammals and nematodes. To facilitate the determination of the molecular basis for host vs parasite differences in PEPCK, we have cloned a cDNA encoding this enzyme from a parasitic nematode of ruminants, Haemonchus contortus. H. contortus PEPCK was cloned by functional complementation of a PEPCK-, malic enzyme- strain of Escherichia coli (E1786) using an egg stage H. contortus cDNA library in lambda ZAPII. Selection was for growth on malate as the sole carbon source (malate+ phenotype). We isolated a plasmid, pPEPCK, which reproducibly confers a malate+ phenotype in E1786. The sequence of the 2.0-kb EcoRI insert of pPEPCK predicts a 612-amino acid protein which shows about 74% similarity to Drosophila melanogaster and chicken PEPCK. Extracts of E1786[pPEPCK], but not E1786, contain IDP- or GDP-dependent PEPCK enzyme activity. Sequence analysis revealed that the open reading frame (ORF) in pPEPCK lacked a 5' initiation codon and was probably expressed as an in-frame fusion protein with beta-galactosidase. A strategy combining library screening with PCR analysis of positive clones led to the identification of a clone encoding 6 additional NH2-terminal amino acids, including a Met, which, by comparison with known PEPCK amino acid sequences, is likely to be the translation initiation site.
Mol Biochem Parasitol 1992 Feb
PMID:Cloning of a cDNA encoding phosphoenolpyruvate carboxykinase from Haemonchus contortus. 174 Oct 16


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