Protein ubiquitination is regulated by phosphorylation. An in vitro study.

Protein ubiquitination has been implicated in ATP-dependent protein turnover and in a number of biological processes in eukaryotic cells. The ubiquitination activating enzyme, E1, and ubiquitin carrier protein, E2, are two essential enzymes in the protein ubiquitination machinery. Using purified E1 and E2 from rabbit reticulocytes and various protein kinases, which include cAMP-dependent protein kinase, protein kinase C, and protein tyrosine kinase, we demonstrated that E1 is phosphorylated by protein kinase C, with a stoichiometry of 0.65 mol of phosphate/mol of E1, and one of the E2 isoforms, E2(32kDa), is phosphorylated by protein tyrosine kinase to 2 eq of phosphate/mol of protein. Phosphorylation of E1 causes a 2-fold enhancement of its activity as monitored by ubiquitin-dependent ATP in equilibrium PPi exchange. When 1 eq of phosphate was incorporated into E2(32kDa), a 2.4-fold activation was also observed for its activity to catalyze the ubiquitination of histone H2A. The regulatory significance of this finding is discussed.     

Immunohistochemical localization of 36 and 29 kDa proteins in sparganum.

Antigenic proteins of 36 and 29 kDa were localized in Spirometra mansoni plerocercoid (sparganum) immunohistochemically by avidin biotin complex (ABC) staining. When polyclonal antibodies such as BALB/c mouse serum immunized with crude saline extract of sparganum or confirmed sparganosis sera were reacted as primary antibodies, the positive chromogen (3-amino, 9-ethylcarbazole) reactions were recognized at syncytial tegument, tegumental cells, muscle and parenchymal cells and lining cells of excretory canals. A monoclonal antibody (MAb) which was reacting to 36 and 29 kDa proteins in the extract of the worm was localized at the syncytial tegument and tegumental cells. The present results suggested that the potent antigenic proteins of 36 and 29 kDa in sparganum were produced at the tegumental cells and transported to the syncytial tegument.     

Chromium distribution in subcellular components between fresh and starved subsurface bacterial consortium

Summary The distribution of chromium in subcellular components was examined with a fresh and starved denitrifying consortium by performing Cr⁺⁶ equilibration and cell fractionation tests. The cell wall fraction of 50 day starved cells adsorbed approximately 100% more chromium than did the cell wall fraction in fresh cells. The soluble fraction of 50 day old cells showed less affinity for chromium than fresh cells.     

Kinetic properties of a L-cysteine desulfhydrase-deficient mutant in the enzymatic formation of L-cysteine from D,L-ATC

Summary A mutant strain lacking in activity of L-cysteine desulfhydrase, a L-cysteine-decomposing enzyme, was screened after UV-treatment ofPseudomonas sp. CU6. The properties of the two strains, original and mutant, were compared on the basis of parameter values estimated from kinetic simulations of the enzymatic formation of L-cysteine from D,L-ATC. Both strains suffered from product inhibition, though inhibition was less for the mutant strain.     

华东地区黑果蝇自然群体同工酶遗传多态的研究

我们用标准垂直板聚丙烯酰胺凝胶电泳和水平板琼脂糖凝胶电泳技术检测了黑果蝇(D.virilis)在合肥、芜湖、九江、南昌、福州、泉州和常州7个自然群体中Est-α、Est-β、Amy、Acph和α-Gpdh 5个座位的遗传变异,发现Est-α、Est-β和Amy 3个座位是高度多态的,Acph、α-Gpdh两个座位则是单态的。根据这5个座位等位基因的频率,我们计算了群体间的遗传距离。综合何朝珍报道的宁波、杭州、南京和洪泽4个群体的结果和我们的结果,我们作出系统树并发现泉州、福州两群体和其他群体在基因频率的分布和遗传距离方面有显著差异;分析显示这种差异与群体间地理隔离有关。     

Interaction of mutagenic spermidine-nitrous acid reaction products with uvr- and recA-dependent repair systems in Salmonella.

It has been observed previously that the mutagenic action of nitrous acid may be potentiated by polyamines. We examined the cellular response of two deoxyribonucleic acid repair systems to treatment with spermidine-nitrite reaction products. uvrB- deficient mutants of Salmonella typhimurium LT2 showed enhanced lethal and mutagenic response to the reaction products. Lethal activity was further enhanced in a uvrB recA double mutant, whereas mutagenic activity was not detectable. Dependence of mutagenesis on the recA gene implicates the action of an error-prone repair system in the fixation of a premutagenic lesion as a mutation. From consideration of the substrate characteristics of the two repair systems studied, it is suggested that the deoxyribonucleic acid lesion formed by the reaction products of spermidine and nitrite is an intrastrand cross-link.     

Inhibition of Ouabain-binding to (Na+ + K+)ATPase by antibody against the catalytic subunit but not by antibody against the glycoprotein subunit

Antibodies against purified ($\text{Na}{}^{\mathrm{+}}\text{+}\text{K}{}^{\mathrm{+}}\text{)}\text{ATPase}$ from the rectal gland of Squalus acanthias, as well as against its catalytic subunit, inhibited ouabain binding by as much as 50%. However, antibodies against the glycoprotein subunit did not inhibit ouabain binding. These data suggest that binding of antibody against the catalytic subunit to the enzyme either covers the ouabain binding site or destroys its conformation, while binding of antibody against the glycoprotein has no such effect.     

The effect of Bordetella pertussis on the antibody response in mice to type III pneumococcal polysaccharide.

The effect of an i.p. injection of Bordetella pertussis on the primary humoral immune response in mice to the thymus-independent antigen SIII has been studied. Suppression of the antibody response occurred when pertussis cells were injected at the same time as an optimal immunizing dose of SIII. In contrast, the antibody response to high doses of SIII was enhanced by B. pertussis. When SIII alone was injected, only 19S antibody was detected. However, when B. pertussis was administered with either optimal or high doses of SIII, 7S as well as 19S antibody against SIII was produced.     

NMR study of in vivo RIF-1 tumors: Analysis of perchloric acid extracts and identification of 1H, 31P and 13C resonances

Perchloric acid extracts of radiation-induced fibrosarcoma (RIF-1) tumors grown in mice have been analyzed by multinuclear NMR spectroscopy and by various chromatographic methods. This analysis has permitted the unambiguous assignment of the ³¹P resonances observed in vivo to specific phosphorus-containing metabolites. The region of the in vivo spectra generally assigned to sugar phosphates has been found in RIF-1 tumors to contain primarily phosphorylethanolamine and phosphorylcholine rather than glycolytic intermediates. Phosphocreatine was observed in extracts of these tumor cells grown in culture as well as in the in vivo spectra, indicating that at least some of the phosphocreatine observed in vivo arises from the tumor itself and not from normal tissues. In the ³¹P-NMR spectra of the perchloric acid extract, resonances originating from purine and pyrimidine nucleoside di- and triphosphate were resolved. HPLC analyses of the nucleotide pool indicate that adenine derivatives were the most abundant components, but other nucleotides were present in significant amounts. The ¹H and ¹³C resonance assignments of the majority of metabolites present in RIF-1 extracts have also been made. Of particular importance is the ability to observe lactate, the levels of which may provide a noninvasive measure of glycolysis in these cells in both the in vivo and in vitro states. In addition, the aminosulfonic acid, taurine, was found in high levels in the tumor extracts.