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21.
Effect of pH on binding of agonists and antagonists to rat heart muscarinic receptors. 总被引:3,自引:0,他引:3 下载免费PDF全文
J Asselin M Waelbroeck P Robberecht P de Neef J Christophe 《The Biochemical journal》1983,216(1):11-19
Insulin, epidermal growth factor (EGF), platelet-derived growth factor, multiplication-stimulating activity and 10% foetal-calf serum each stimulated the phosphorylation of a cytosolic Mr-22000 acidic heat-stable protein in Swiss mouse 3T3-L1 adipocytes. Phosphorylation of this protein was not stimulated by isoprenaline or dibutyryl cyclic AMP. The effect of insulin was maximal (3-fold increase) by 10 min; half-maximal stimulation was observed at 70 pM-insulin. Both [32P]phosphoserine and [32P]phosphothreonine residues were present in the Mr-22000 protein after insulin- and growth-factor-stimulated phosphorylation, but no [32P]phosphotyrosine. The major site of insulin- and EGF-stimulated phosphorylation appeared to be a threonine residue, in contrast with previously studied insulin-stimulated phosphorylation of serine residues. Insulin treatment appeared to result in a shift of the protein toward the anode on isoelectric focusing. Insulin and EGF present simultaneously did not lead to phosphorylation beyond that seen with each hormone singly. We surmise that insulin, EGF and perhaps other growth factors may activate a common protein kinase or inhibit a common protein phosphatase in 3T3-L1 adipocytes which acts on the Mr-22000 protein. 相似文献
22.
W J Malaisse A Sener M Welsh F Malaisse-Lagae C Hellerstrm J Christophe 《The Biochemical journal》1983,210(3):921-927
1. The metabolism and metabolic effects of 3-phenylpyruvate were examined in rat pancreatic islets. 2. Islet homogenates catalysed transamination reactions between 3-phenylpyruvate and L-glutamate, L-leucine, L-norleucine or L-valine. 3-Phenylpyruvate failed to activate glutamate dehydrogenase. 3. 3-Phenylpyruvate rapidly entered into islet cells, was extensively converted into phenylalanine but slowly oxidized. 4. The conversion of phenylpyruvate into phenylalanine coincided with a fall in the content of several amino acids (especially glutamate and aspartate) in the islets and incubation medium, the accumulation of 2-oxoglutarate and a modest fall in the NH4+ production rate. 5. 3-Phenylpyruvate failed to affect 14CO2 output from islets prelabelled with [U-14C]palmitate, but augmented 14CO2 output from islets prelabelled or incubated with L-[U-14C]glutamine. 6. In the presence of L-glutamine, 3-phenylpyruvate augmented the ATP/ADP ratio and NAD(P)H islet content, and caused a rapid and sustained decrease in the outflow of radioactivity from islets prelabelled with [2-3H]adenosine. 7. These data support the view that the insulin-releasing capacity of 3-phenylpyruvate coincides with an increase in the catabolism of endogenous amino acids acting as 'partners' in transamination reactions leading to the conversion of 3-phenylpyruvate into phenylalanine. 相似文献
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Jan Klein Christophe Benoist Chella S. David Peter Demant Kirsten Fischer Lindahl Lorraine Flaherty Richard A. Flavell Ulrich Hämmerling Leroy E. Hood Stephen W. Hunt III Patricia P. Jones Philippe Kourilsky Hugh O. McDevitt Daniel Meruelo Donal B. Murphy Stanley G. Nathenson David H. Sachs Michael Steinmetz Susumu Tonegawa Edward K. Wakeland Elizabeth H. Weiss 《Immunogenetics》1990,32(3):147-149
27.
C Delporte J Winand P Poloczek E Brunko M Tastenoy M Waelbroeck J Christophe 《Biochimica et biophysica acta》1992,1135(3):323-329
ATP dose-dependently inhibited rat 125I-ANP-(99-126) binding to membranes from the human neuroblastoma cell line NB-OK-1 by increasing the KD value for the hormone without altering the Bmax value. After a 20 min preincubation with 37.5 pM 125I-ANP-(99-126) and 0.5 mM ATP, followed by the addition of 0.3 microM unlabelled ANP-(99-126), the proportion of rapidly dissociating receptors was 4-times higher than in the absence of ATP. The other nucleotides ADP, AMP, AMP-PNP, ATP gamma S, GTP, GDP, GMP, GMP-PNP and GTP gamma S were also inhibitory but with a lower potency and/or efficacy. Binding equilibrium data were satisfactorily simulated by a computer program based on partially competitive binding of ANP-(99-126) and the nucleotides, and this, together with the data on dissociation kinetics, strongly suggests that several nucleotides, when added at concentrations up to 1 mM, form a ternary ANP-receptor-nucleotide complex. 相似文献
28.
Rat PHI, PHI-GLY and PHV (1-42) stimulate adenylate cyclase in six rat tissue and cell membranes 总被引:1,自引:0,他引:1
A Cauvin M C Vandermeers-Piret A Vandermeers E Coussaert P de Neef P Robberecht J Christophe 《Peptides》1990,11(5):1009-1014
PHI and the two C-terminally extended forms PHI-GLY and PHV(1-42) coexist in rat tissues. We compared the relative potency and efficacy of these three PHI forms and of VIP to stimulate adenylate cyclase activity and, when feasible, to occupy VIP receptors in six rat tissue and cell membranes. With the exception of lung membranes, all three PHI forms were markedly less potent than VIP but all were systematically as efficacious. PHI-GLY and PHV(1-42) were never more potent than PHI itself and their relative potencies revealed four spectra, depending on the membrane preparation tested: 1) PHI = PHI-GLY = PHV(1-42) in hepatic, pulmonary and pancreatic membranes; 2) PHI greater than PHV(1-42) = PHI-GLY in membranes from circulating lymphocytes; 3) PHI = PHV(1-42) greater than PHI-GLY in membranes from the thymocyte cell line 51E; and 4) PHI greater than PHI-GLY = PHV(1-42) in anterior pituitary membranes. These results indicate that the two naturally observed C-terminal extensions of rat PHI variously affected peptide potency on 6 rat membrane preparations. 相似文献
29.
Christophe F. Deroanne Alain C. Colige Betty V. Nusgens Charles M. Lapiere 《Experimental cell research》1996,224(2):215
A model of collagen-inducedin vitroangiogenesis was used to investigate the modulation of expression and assembly of focal adhesion plaque-associated proteins during the process of differentiation. Human umbilical vein endothelial cells (HUVEC), first attached on an adhesive substratum (gelatin-, fibronectin-, or laminin-coated dish) or adherent collagen gel and then covered by an overlaying collagen gel, organized within 3–4 days in tube-like structures (TLS). Removing the overlaying collagen gel from fully differentiated HUVEC induced a reversion of the process and HUVEC returned to a monolayer pattern. Modulations of focal adhesion-associated proteins occurring in HUVEC during thein vitrodifferentiation process and its reversal were investigated by Western blot analysis. A significant decrease of expression of vinculin, the integrin α2subunit, talin, α-actinin, and actin was observed in TLS whereas the amount of FVIII-related antigen did not vary as compared to control monolayer cultures. During reversal, all the reduced proteins were markedly reexpressed. Human skin fibroblasts (HSF), submitted to the same experimental conditions, did not form TLS. Most of the focal adhesion proteins in HSF were similarly modulated by an overlaying collagen gel with the exception of vinculin, which was not modified. This particular protein was therefore more thoroughly investigated. In a nondifferentiated monolayer of HUVEC, a significant proportion of vinculin was organized into a detergent-resistant juxtamembranous structure (focal adhesion plaque) which disassembled early in TLS formation and reassembled during the reversal of the process. The reduction of vinculin during TLS formation was preceded by a downregulation of its mRNA while this mRNA was upregulated during reversal of the morphotype. These results suggest that the modulations of the cytoskeletal and focal adhesion proteins and more specifically of vinculin coupled to its subcellular redistribution are critical and early events in the cascade of mechanochemical signaling duringin vitroangiogenesis induced by fibrillar collagen. 相似文献
30.
Joumana El-Turk Omorefe Asemota Juliette Leymarie Christophe Sallaud Stéphane Mesnage Colette Breda Dominique Buffard Adam Kondorosi Robert Esnault 《Gene》1996,170(2):213-216
We constructed an alfalfa cDNA library from mRNA extracted from leaves after infection with Pseudomonas syringae (incompatible interaction). Screening with oligodeoxyribonucleotides designed from regions conserved in all known peroxidases allowed the isolation of four cDNAs (MsprxlA, 1B, 1C and 2). Sequence analysis revealed the presence of open reading frames of 351, 355, 358 and 323 amino acids, respectively, with the characteristic consensus sequences of plant peroxidases. Sequence comparison showed that the Msprx2 product is significantly different from the others and, particularly, lacks a C-terminal propeptide which might be required for vacuolar targeting. 相似文献