1,721,047 research outputs found
Purification of tyrosine phosphorylated proteins by immunoaffinity chromatography and direct cloning of their cDNAs from bacterial expression libraries
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Tyrosine phosphorylation of Eps15 is required for ligand-regulated but not for constitutive endocytosis
No full textTyrosine phosphorylation of Eps15 is required for ligand-regulated but not for constitutive endocytosis
No full textPulsed and continuous wave 9.4 GHz high intensity microwave exposure effects on cell cultures
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Inhibition off Dimethyl Sulffoxide-induced Differentiation off Friend Erythroleukemic Cells by 5'-Methylthioadenosine
No full text5' -Methylthioadenosine is a sulfur-containing nucleoside derived from the metabolism of polyamines which is known to exert an antiproliferative effect on several cell systems in vitro, including the Friend leukemia cell system. We have investigated the role of 5'-methylthioadenosine on the dimethyl sulfoxRJe-induced differentiation of this system. At a concentration of 400 /*M, the drug strongly inhibited (80%) the induced differentiation of Friend cells, and this effect was already observable at a concentration as tow as 10 HM (36% inhibition), as evidenced by the benzidine staining procedure and by the dot-blot hybridization of globin mRNA with a human 0-globin probe. Similar results have been obtained by using 5'-S-isobutylthioadenosine, which is a synthetic structural analogue of 5' -methylthioadenosine. The block of differentiation produced by these nucleosides was not mediated by adenine (a cataboiite of both molecules) and was not reverted by spermine or spermidine, the two polyamines whose synthesis is inhibited by 5'-methylthtoadenosine. We report a decrease of the aminopropyttransferases activities (the enzymes responsible for 5'-methytthioadenosine biosynthesis) in dimethyl sulfoxide-treated Friend cells, which could lead to a decrease of the intracellular content of 5'-methylthioadenosine during the erythrokJ maturation of Friend cells. The results obtained are consistent with the hypothesis that 5'-methylthioadenosine may act as an endogenous regulator of Friend cell differentiation. © 1984, American Association for Cancer Research. All rights reserved
UBPY: a growth regulated human ubiquitin isopeptidase
No full textThe ubiquitin pathway has been implicated in the regulation of the abundance of proteins that control cell growth and proliferation. We have identified and characterized a novel human ubiquitin isopeptidase, UBPY, which both as a recombinant protein and upon immunoprecipitation from cell extracts is able to cleave linear or isopeptide-linked ubiquitin chains. UBPY accumulates upon growth stimulation of starved human fibroblasts, and its levels decrease in response to growth arrest induced by cell-cell contact. Inhibition of UBPY accumulation by antisense plasmid microinjection prevents fibroblasts from entering S-phase in response to serum stimulation. By increasing or decreasing the cellular abundance of UBPY or by overexpressing a catalytic site mutant, we detect substantial changes in the total pattern of protein ubiquitination, which correlate stringently with cell proliferation. Our results suggest that UBPY plays a role in regulating the overall function of the ubiquitin-proteasome pathway. Affecting the function of a specific UBP in vivo could provide novel tools for controlling mammalian cell proliferation
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