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

Plastocyanin can be detected in Synechocystis sp. PCC 6803 when 3 microM copper is added to the growth medium, BG-11. The plastocyanin gene (petE) was cloned from a genomic lambda EMBL 3 library by screening with the petE gene from Anabaena sp. PCC 7937. The Synechocystis 6803 petE gene is present as a single copy and, as deduced from the DNA sequence, encodes a precursor protein of 126 amino acids. The predicted 29 amino acid transit peptide shows substantial homology to the Anabaena 7937 transit peptide, thought to direct the plastocyanin precursor to the thylakoid lumen. Putative promoter sites -16 and -38 base pairs from the start of the petE gene have been identified. The deduced amino acid sequence has the greatest homology (61%) to the green alga Scenedemus obliquus plastocyanin. Despite the lower homology, the copper binding residues and certain aromatic residues remain highly conserved. Northern hybridization analysis indicates that the Synechocystis sp. PCC 6803 petE gene is not transcriptionally regulated since the accumulation of petE mRNA appears to be independent of the copper concentration in the growth media. The possibility of an additional polypeptide needed to facilitate the electron transfer from plastocyanin to P700+ is also discussed.
Plant Mol Biol 1990 Oct
PMID:Copper-induced expression, cloning, and regulatory studies of the plastocyanin gene from the cyanobacterium Synechocystis sp. PCC 6803. 212 38

Synechocystis sp. PCC 6803 is capable of facultative photoheterotrophy with glucose as the sole carbon source. Eight mutants that were unable to take up glucose were transformed with plasmids from pooled gene banks of wild-type Synechocystis DNA prepared in an Escherichia coli vector that does not replicate in Synechocystis. One mutant (EG216) could be complemented with all gene banks to restore ability for photoheterotrophic growth. One of the gene banks was fractionated into single clones and plasmid DNA from each clone used to complement EG216. This yielded a 1.5 kb DNA fragment that was sequenced. It contained one complete open reading frame (gtr) whose putative gene product displayed high sequence conservation with the xylose transporter of E. coli and the mammalian glucose transporters. Further, the isolated gtr gene interrupted in vitro by a kanamycin resistance cassette could be used to construct mutants from wild-type Synechocystis sp. PCC 6803 that lacked a functional glucose transporter, thus confirming the identity of the gtr gene with the glucose transporter gene. This is the first prokaryotic glucose transporter known to share a sequence relationship with mammalian glucose transporters and the first sugar transporter from a cyanobacterium characterized at the sequence level.
Plant Mol Biol 1990 May
PMID:Sequence conservation among the glucose transporter from the cyanobacterium Synechocystis sp. PCC 6803 and mammalian glucose transporters. 212 97

We have examined the binding of factors in rat liver nuclear extracts to the phosphoenolpyruvate carboxykinase (PEPCK) gene cyclic AMP (cAMP) response element (CRE) and other CREs and have isolated a rat liver CRE-binding protein (CREBP) cDNA. In addition, we have examined the influence of altering the phosphorylation state of nuclear factors on both CRE binding and in vitro transcription. Specific binding to the PEPCK CRE was measured in a mobility shift assay. CRE sequences of the PEPCK, somatostatin, and glycoprotein hormone alpha subunit genes competed equally for binding of rat liver nuclear factors to the PEPCK CRE, whereas mutant PEPCK CRE sequences did not compete for binding. Oligonucleotides complementary to rat pheochromocytoma CREBP (Gonzalez et al., Nature [London] 337:749-752, 1989) were used to prime rat liver and brain cDNA in the polymerase chain reaction. The predominant CREBP molecule obtained was identical to the rat pheochromocytoma CREBP except for a 14-amino-acid deletion in the N-terminal half that was also present in a human placental cDNA (Hoeffler et al., Science 242:1430-1433, 1988). The regulation of transcription by cAMP was examined by coincubation of rat liver nuclear extract with the purified catalytic subunit of cAMP-dependent protein kinase (protein kinase A). Although binding to the CRE was unaffected, in vitro transcription directed by the PEPCK promoter was stimulated by catalytic subunit, and this effect was blocked by protein kinase inhibitor peptide. In contrast, when nuclear extract was coincubated with phosphatase, there was substantial inhibition of in vitro transcription directed by the PEPCK promoter, but there was no effect on binding to the CRE. The major effects of catalytic subunit were exerted through the CRE, but residual stimulation was evident in promoter fragments containing only the TATA element. These data suggest that factors are bound to the CRE at constitutively high levels and that their capacity for transcriptional activation is regulated by phosphorylation.
Mol Cell Biol 1990 Jul
PMID:Cyclic AMP-dependent protein kinase regulates transcription of the phosphoenolpyruvate carboxykinase gene but not binding of nuclear factors to the cyclic AMP regulatory element. 214 84

The neuronal growth associated protein GAP-43 is expressed at high levels during axonal growth and regeneration. In this report, we describe the transfection of the nerve growth factor (NGF)-responsive pheochromocytoma cell line PC12 with the human GAP-43 cDNA under the control of the Moloney murine leukemia virus long terminal repeat (MoMuLV LTR). Two PC12 subclones were isolated that constitutively expressed GAP-43 from the transfected cDNA and showed increased responsiveness to NGF. Of the two transfected PC12 subclones, the subclone expressing the most human GAP-43 RNA showed an accelerated initial neurite outgrowth response and a 10-fold increased sensitivity to NGF. Neurite regeneration was significantly enhanced in both transfected subclones and, in contrast to untreated PC12 cells, could occur transiently in the absence of added NGF. These results suggest that GAP-43 may potentiate the action of NGF on neurite initiation and regeneration.
Brain Res Mol Brain Res 1990 Jan
PMID:Transfection of PC12 cells with the human GAP-43 gene: effects on neurite outgrowth and regeneration. 215 93

Maitotoxin (MTX) increases formation of [3H]inositol phosphates from phosphoinositides and release of [3H]arachidonic acid from phospholipids in pheochromocytoma PC12 cells. Formation of [3H]inositol phosphates is detected within 1 min of incubation even with concentrations as low as 0.3 ng/ml (90 pm) MTX, whereas release of [3H]arachidonic acid is not detected until 20 min even with concentrations as high as 1 ng/ml (300 pm) MTX. Stimulation of arachidonic acid release can be detected at 0.03 ng/ml (9 pm) MTX, whereas 0.1 ng/ml (30 pm) MTX is the threshold for detection of phosphoinositide breakdown. Organic and inorganic calcium channel blockers, except Cd2+ and a high concentration of Mn2+, have no effect on MTX-elicited phosphoinositide breakdown, whereas inorganic blockers (e.g., Co2+, Mn2+, Cd2+), but not organic blockers (nifedipine, verapamil, diltiazem), inhibit MTX-stimulated arachidonic acid release. All calcium channel blockers, however, inhibited MTX-elicited influx of 45Ca2+ and the MTX-elicited increase in internal Ca2+ measured with fura-2 was markedly reduced by nifedipine. MTX-elicited phosphoinositide breakdown and arachidonic acid release are abolished or reduced, respectively, in the absence of extracellular calcium plus chelating agent. The calcium ionophore A23187 has little or no effect alone but, in combination with MTX, A23187 inhibits MTX-elicited phosphoinositide breakdown and enhances arachidonic acid release, the latter even in the absence of extracellular calcium. The results suggest that different sites and/or mechanisms are involved in stimulation of calcium influx, breakdown of phosphoinositides, and release of arachidonic acid by MTX.
Mol Pharmacol 1990 Feb
PMID:Maitotoxin: effects on calcium channels, phosphoinositide breakdown, and arachidonate release in pheochromocytoma PC12 cells. 215 71

Nerve growth factor (NGF) affects levels of the alpha subunit of the stimulatory G protein (Gs-alpha) in pheochromocytoma 12 cells in a bidirectional, density-dependent manner. Cells grown at high density responded to NGF treatment with increased levels of Gs-alpha mRNA and protein. Conversely, in cells grown in low-density cultures, levels of this mRNA were lowered by NGF treatment.
Mol Cell Biol 1990 Jun
PMID:Density-dependent nerve growth factor regulation of Gs-alpha RNA in pheochromocytoma 12 cells. 216 May 99

The regulation of the preproneuropeptide Y gene (NPY gene) by nerve growth factor (NGF) and second messenger systems in PC12 rat pheochromocytoma cells was studied by means of steady state NPY mRNA and nuclear run-on transcription analyses. Treatment of cells with 2.5S NGF increased the NPY mRNA abundance up to 100-fold over 1-6 days. Glucocorticoids (e.g. dexamethasone) potentiated by up to 3-fold the stimulation by NGF at early times (less than or equal to 7 h), but strongly suppressed it at later times (greater than or equal to 25 h). The response to NGF was blocked by cycloheximide, indicating a requirement for ongoing protein synthesis. Treatment of cells for 24-48 h with combinations of NGF, forskolin to elevate cAMP levels, and phorbol-12-myristate-13-acetate (PMA) to activate protein kinase C synergistically elevated NPY mRNA levels. The rate of NPY gene transcription in PC12 nuclei was increased by NGF, forskolin plus PMA, or NGF plus forskolin plus PMA, indicating that these regulators act at least in part at a transcriptional level. beta-Actin gene transcription also was elevated synergistically by forskolin and PMA. In summary, NPY gene transcription and NPY mRNA levels are controlled by multiple, potentially interacting regulatory systems. The striking antagonism between NGF and glucocorticoids may reflect the hormonal control of phenotypic choice during neural crest differentiation.
Mol Endocrinol 1990 Mar
PMID:Transcriptional regulation of the neuropeptide Y gene by nerve growth factor: antagonism by glucocorticoids and potentiation by adenosine 3',5'-monophosphate and phorbol ester. 216 Jun 1

The interaction of methylmercury (MeHg) with neuronal Ca2+ channels in rat forebrain synaptosomes and dihydropyridine (DHP)-sensitive Ca2+ channels in rat pheochromocytoma (PC12) cells was examined using radiotracer flux assays and radioligand binding analyses. In synaptosomes, the influx of 45Ca2+ was used to examine the voltage and state dependence of block of Ca2+ channels by MeHg, as well as the effects of MeHg on apparent inactivation of 45Ca2+ influx. In addition, the differential influx of 45Ca2+, 85Sr2+, and 133Ba2+ was used to examine the effect of MeHg on the ionic selectivity of synaptosomal Ca2+ channels. The ability of MeHg to block 45Ca2+ influx via a DHP-sensitive Ca2+ channel was examined in PC12 cells. Effects of MeHg on binding of [3H]nitrendipine in synaptosomes and 125I-omega-conotoxin GVIA (CgTx) in synaptosomes and PC12 cells were measured. In synaptosomes, MeHg blocked 45Ca2+ influx in a voltage-dependent manner, inasmuch as increasing the extracellular K+ concentration increased the magnitude of block by 100 microM MeHg. When synaptosomes were incubated for 10 sec in either a nondepolarizing or a depolarizing solution before measurement of 1 sec of depolarization-induced 45Ca2+ influx, the potency and efficacy of the block of 45Ca2+ influx by MeHg were similar. Thus, block of Ca2+ channels by MeHg does not appear to be state dependent. To determine the kinetics of apparent inactivation of 45Ca2+ influx, synaptosomes were predepolarized in Ca2(+)-free high [K+] solution, for intervals varying from 1 to 10 sec, before measurement of 1 sec of K(+)-induced 45Ca2+ influx. When compared with control, MeHg (100 microM) altered the rate constant for apparent inactivation and decreased the fraction of 45Ca2+ influx that does not inactivate. Influx of 45Ca2+, 85Sr2+, and 133Ba2+ during 1 sec of depolarization was blocked in a dose-dependent manner by MeHg, with estimated IC50 values of 125, 150, and greater than 150 microM for 45Ca2+, 85Sr2+, and 133Ba2+, respectively. In triple-label experiments, the relative flux of radiolabeled Ca2+:Sr2+:Ba2+ was altered from approximately 6:2:3 to 6:1:3 in the presence of 100 microM MeHg. In undifferentiated and nerve growth factor-differentiated PC12 cells, K(+)-induced 45Ca2+ influx was blocked by the DHP nifedipine, with an approximate IC50 value of 5 nM. MeHg reduced 45Ca2+ influx in PC12 cells with an estimated IC50 value of 50 microM, and 125 microM MeHg reduced uptake by greater than 90%. [3H]Nitrendipine bound to synaptosomes with high affinity in normal and elevated [K+] solutions.(ABSTRACT TRUNCATED AT 400 WORDS)
Mol Pharmacol 1990 Jul
PMID:Characterization of interactions of methylmercury with Ca2+ channels in synaptosomes and pheochromocytoma cells: radiotracer flux and binding studies. 216 28

Localization of the regulatory subunit of cAMP-dependent protein kinase type II was studied in proliferating and quiescent fibroblasts 3T3 and in a cell line of neural origin pheochromocytoma PC12. In actively proliferating PC12 cells the regulatory subunit was found to be localized in the nucleus. Transition of these cells into a quiescent state was accompanied by a regulatory subunit translocation to the cytoplasm. In 3T3 cells the regulatory subunit was localized in the cytoplasm both in the quiescent and proliferating (though less actively than PC12 cells) states. Similar results were obtained both with monoclonal antibodies and with rabbit monospecific antiserum raised against the regulatory subunit type II from pig brain.
Mol Cell Biochem 1990 Mar 05
PMID:Immunofluorescence localization of the regulatory subunit type II of cAMP-dependent protein kinase in PC12 and 3T3 cells in different proliferative states. 218 46

Expression of the N-ras oncogene under the control of the glucocorticoid-responsive promoter in the pheochromocytoma cell line UR61, a subline of PC-12 cells, has been used to investigate the differentiation process to neuronal cells triggered by ras oncogenes (I. Guerrero, A. Pellicer, and D. E. Burstein, Biochem. Biophys. Res. Commun. 150:1185-1192, 1988). Using ras-inducible cell lines, we observed that expression of the oncogenic N-ras p21 protein interferes with the ability of phorbol esters to induce downregulation of protein kinase C. This effect was associated with the appearance of immunologically detectable protein kinase C as well as the activity of the enzyme as analyzed either by binding of [3H]phorbol-12,13-dibutyrate in intact cells or by in vitro kinase activity. These results indicate a relationship between ras p21 and protein kinase C in neuronal differentiation in this model system. Comparison to the murine fibroblast system suggests that this relationship may be functional.
Mol Cell Biol 1990 Jun
PMID:Regulation of protein kinase C activity in neuronal differentiation induced by the N-ras oncogene in PC-12 cells. 218 5


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