scholarly journals Inhibition of protein synthesis in frog (Xenopus laevis) egg extracts by an antibody against phosphatidylinositol 4,5-bisphosphate

1996 ◽  
Vol 317 (3) ◽  
pp. 643-646
Author(s):  
Thomas J. KEATING ◽  
Kiyoko FUKAMI ◽  
Kenneth R. ROBINSON
Keyword(s):  
Protein Synthesis ◽  
Xenopus Laevis ◽  
Similar Reduction ◽  
Inhibition Of Protein Synthesis ◽  
Egg Extracts ◽  
Hydrolysis Of

The antibody kt10, which is directed against the phospholipid PtdIns(4,5)P2, inhibits protein synthesis when added to cytosolic extracts prepared from frog eggs. Addition of stable analogues of diacylglycerol and Ins(1,4,5)P3 failed to rescue the inhibition of translation, suggesting that the effect of the antibody was not to block hydrolysis of PtdIns(4,5)P2. Neomycin, which also binds PtdIns(4,5)P2, produced a similar reduction in protein-synthesis levels in the extract system, supporting the idea that it is the interaction of the antibody with PtdIns(4,5)P2 that is producing the effect.

Effect of 3-deazaadenosine on methionine metabolism in isolated perfused livers

1988 ◽  
Vol 66 (10) ◽  
pp. 1032-1039 ◽  
Author(s):  
John A. Duerre
Keyword(s):  
Protein Synthesis ◽  
Specific Radioactivity ◽  
Carbon Chain ◽  
Methionine Metabolism ◽  
Equivalent Amount ◽  
Purine Analog ◽  
Inhibition Of Protein Synthesis ◽  
Hydrolysis Of ◽  
Sulfur Containing ◽  
Sulfur Containing Compounds

The effect of the purine analog 3-deazaadenosine (dzAdo) on the metabolism of sulfur-containing compounds was examined in hepatocytes. The uptake of exogenous methionine by the liver was not affected by the addition of dzAdo to the perfusate, while the intracellular concentrations of S-adenosyl-L-methionine (AdoMet) and S-adenosyl-L-homocysteine (AdoHcy) continued to increase as long as exogenous methionine was available. In addition, large amounts of 3-deazaadenosyl-L-homocysteine (dzAdoHcy) accumulated in the cell. The specific radioactivity of the carbon chain of dzAdoHcy was the same as that of AdoMet and AdoHcy. Consequently, an equivalent amount of homocysteine (Hey) must have been generated via hydrolysis of AdoHcy. Free Hey could not be detected either in the tissue or perfusate when dzAdo was present, while Hey was excreted into the perfusate by control livers. Consequently, the AdoHcy and DzAdoHcy that accumulate in the cell not only function as inhibitors of methylation reactions, but serve as a trap for Hey. This could result in methionine starvation and hence, inhibition of protein synthesis.

scholarly journals REFORMATION OF NUCLEOLI AFTER ETHIONE-INDUCED FRAGMENTATION IN THE ABSENCE OF SIGNIFICANT PROTEIN SYNTHESIS

1969 ◽  
Vol 41 (1) ◽  
pp. 280-286 ◽  
Author(s):  
Hisashi Shinozuka ◽  
Emmanuel Farber
Keyword(s):  
Protein Synthesis ◽  
Xenopus Laevis ◽  
Rat Liver ◽  
Actinomycin D ◽  
Compact Mass ◽  
Early Stages ◽  
Nucleolar Organization ◽  
Inhibition Of Protein Synthesis ◽  
Fibrillar Component

The rat liver nucleolus, after fragmentation induced by ethionine treatment, has been found to undergo complete reformation by adenine in the presence of a dose of cycloheximide sufficient to cause inhibition of protein synthesis by 90–95%. In contrast, actinomycin D given along with adenine was followed by the appearance of a small compact mass containing only the fibrillar component with no evident granules. This structure resembled pseudonucleoli seen in the anucleolate mutant of Xenopus laevis or in certain early stages of amphibian oocytes. Actinomycin D administered 2 hr after adenine induced a segregation of the fibrillar and granular components of nucleoli similar to that induced in the normal nucleolus. The implications of these findings in relation to nucleolar organization are briefly discussed.

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