References of "Martial, Joseph"
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See detailRegulation of growth hormone messenger RNA by thyroid and glucocorticoid hormones
Martial, Joseph ULg; Baxter, John D; Goodman, Howard M et al

in Proceedings of the National Academy of Sciences of the United States of America (1977), 74(5), 1816-20

Thyroid and glucocorticoid hormones stimulate growth hormone synthesis in cultured rat pituitary cells (GC). We have compared changes in growth hormone production and mRNA in these cells. Triiodothyronine ... [more ▼]

Thyroid and glucocorticoid hormones stimulate growth hormone synthesis in cultured rat pituitary cells (GC). We have compared changes in growth hormone production and mRNA in these cells. Triiodothyronine (10 nM) and dexamethasone (1 micron) stimulated increases in growth hormone production by 2.5- and 3.8-fold, respectively. There were corresponding increases in the capacity of RNA from hormone-treated cells to direct synthesis of pregrowth hormone in a wheat germ cell-free translation system, suggesting hormone-regulated increases in growth hormone mRNA. Hormone-induced changes in mRNA were also demonstrated by determining the kinetics of hybridization of a cDNA probe prepared from RNA enriched (about 70%) for growth hormone translational activity with RNA from control and hormone-treated cells. These results suggest that thyroid and glucocorticoid hormones can regulate growth hormone production by influencing the levels of its mRNA. [less ▲]

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See detailActivity and Subcellular Distribution of Protein Kinase Dependent on Adenosine 3': 5'-Monophosphate in Liver from Normal and Adrenalectomized Rats
Rousseau, Guy; Martial, Joseph ULg; De Visscher, M.

in European Journal of Biochemistry (1976), 66(3), 499-506

We have examined whether glucocorticoids control the activity and (or) the subcellular distribution of protein kinase dependent on cyclic AMP (adenosine 3':5'-monophosphate), since they influence cyclic ... [more ▼]

We have examined whether glucocorticoids control the activity and (or) the subcellular distribution of protein kinase dependent on cyclic AMP (adenosine 3':5'-monophosphate), since they influence cyclic-AMP-dependent responses to other hormones. Protein kinase activity was determined in rat liver homogenates and subcellular fractions, nuclear, large granular, microsomal and supernatant obtained by differential sedimentation in 0.25 M sucrose. 63% of the tissue protein kinase activity detected in absence of cyclic AMP reside in the particulate fractions. Upon addition of exogenous cyclic AMP, protein kinase activity is stimulated 1.8, 1.2, 1.2 and 4.5-fold in nuclear, large granular, microsomal and supernatant fractions, respectively. Under these conditions, 66% of tissue activity are found in the supernatant fraction. The activity sensitive to exogenous cyclic AMP resolves into a major (84%) cytosoluble and a minor (16%) nucleomicrosomal component. The latter activity resists elution with isotonic saline and is increased in the presence of Triton X-100. Three groups of rats were studied: control and adrenalectomized with or without cortisol treatment. In whole liver homogenates, both protein kinase activity detected in absence of exogenous cyclic AMP and sensitivity of the enzyme to cyclic AMP were comparable in all groups. Moreover, the distribution patterns of proteins kinase activity amoung the fractions were essentially the same in all groups of animals, whether or not particles had been treated with Triton X-100. Finally, in cell-free experiments, glucocorticoids alone or in combination with their intracellular receptor did not modify protein kinase activity of rat liver. Thus the results reported do not support the possibility that glucocorticoids influence cyclic AMP-dependent protein kinase in rat liver. Yet, this study provides data, not available before, on subcellular distribution of this enzyme in rat liver. [less ▲]

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See detailInactivation of rat liver RNA polymerases I and II and yeast RNA polymerase I by pyrodixal 5'-phosphate. Evidence for the participation of lysyl residues at the active site.
Martial, Joseph ULg; Zaldivar, J.; Bull, P. et al

in Biochemistry (1975), 14

Purified DNA-dependent RNA polymerase forms I (A) and II (B) from rat liver and form I from yeast are rapidly inactivated by pyridoxal 5'-phosphate at pH 8.0. The inhibition is relatively specific since ... [more ▼]

Purified DNA-dependent RNA polymerase forms I (A) and II (B) from rat liver and form I from yeast are rapidly inactivated by pyridoxal 5'-phosphate at pH 8.0. The inhibition is relatively specific since pyridoxamine 5'-phosphate is not an inhibitor and pyridoxal is about 12 times less effective than pyridoxal 5'-phosphate. The inactivation is reversed by high concentrations of amines, and can be made irreversible by reduction with NaBH4. Spectral analysis of the inhibited enzyme and its NaBH4 reduction product indicates that a Schiff base forms between the aldehyde group of pyridoxal 5'-phosphate and one or more amino groups of the protein. Nepsilon-Pyridoxyllysine was identified as the only product in acid hydrolysates of the reduced yeast RNA polymerase I-pyridoxal 5'-phosphate complex. Complete inactivation of yeast polymerase I results in the incorporation of 3-4 mol of pyridoxal 5'-phosphate/1 mol of enzyme. DNA and nucleotide substrates partially protect the enzymes from inactivation. These results suggest that one or more lysyl amino groups are critical for the activity of animal RNA polymerases and show that pyridoxal 5'-phosphate is a suitable probe for studying the active sites of these enzymes. Comparison of the present results with those previously obtained with Eschericha coli RNA polymerase in this laboratory suggest a new degree of structural homology between eucaryotic and procaryotic RNA polymerases. [less ▲]

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See detailInactivation of E. coli RNA polymerase by pyridoxal 5′-phosphate: Identification of a low pKa lysine as the modified residue
Bull, Paulina; Zaldivar, Josefina; Venegas, Alejandro et al

in Biochemical and Biophysical Research Communications (1975), 64(4), 1152-1159

The inactivation of E. coli RNA polymerase (3.3 × 10−7M) by pyridoxal 5′-phosphate (1 × 10−4M to 5 × 10−4M) is a first order process with respect to the remaining active enzyme. Studies of the variation ... [more ▼]

The inactivation of E. coli RNA polymerase (3.3 × 10−7M) by pyridoxal 5′-phosphate (1 × 10−4M to 5 × 10−4M) is a first order process with respect to the remaining active enzyme. Studies of the variation of the first order rate constant with the concentration of pyridoxal 5′-phosphate show that the inactivation reaction follows saturation kinetics. The formation of a reversible enzyme-inhibitor intermediate is postulated. Kinetic studies at different pH values indicate that the inactivation rate constant depends on the mole fraction of one conjugate base with pKa 7.9. The apparent equilibrium constant (association) for the inactivation reaction is independent of the pH and is 1.8 × 104 M−1. By electrophoretic and chromatographic analysis of enzyme hydrolyzates after pyridoxal 5′-phosphate and NaBH4 treatment only N-ε-pyridoxyllysine was found. It is postulated that a lysine ε-amino group with a low pKa is critical for the activity of the enzyme. [less ▲]

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See detailActive site-directed inhibition of E. coli DNA-dependent RNA polymerase by pyridoxal 5′-phosphate
Venegas, Alejandro; Martial, Joseph ULg; Valenzuela, Pablo

in Biochemical and Biophysical Research Communications (1973), 55(4), 1053-1059

DNA-dependent RNA polymerase from E. coli is rapidly inhibited by preincubation with pyridoxal 5′-phosphate. The enzyme is not inhibited by pyridoxamine 5′-phosphate or pyridoxine. Pyridoxal is about 10 ... [more ▼]

DNA-dependent RNA polymerase from E. coli is rapidly inhibited by preincubation with pyridoxal 5′-phosphate. The enzyme is not inhibited by pyridoxamine 5′-phosphate or pyridoxine. Pyridoxal is about 10 times less effective than pyridoxal 5′-phosphate. Nucleoside triphosphates but not DNA, protect the enzyme from inhibition. Spectral data from the reaction mixture and NaBH4 reduction products indicate the formation of a Schiff base between the aldehyde group of pyridoxal 5′-phosphate and amino group of the enzyme. The results show that the inhibitor is reacting with a critical amino group presumably at the nucleoside phosphate binding site of the active center of the enzyme. [less ▲]

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