Effect of soman intoxication on the organization of rat brain ribosomes and the translational activity of mRNA in a cell-free system

1989 ◽  
Vol 63 (3) ◽  
pp. 244-247 ◽  
Author(s):  
Ljiljana Ševaljević ◽  
Bogdan Bošković ◽  
Marija Glibetić ◽  
Mirko Tomić
Keyword(s):  
Rat Brain ◽  
Free System ◽  
Cell Free System ◽  
Translational Activity ◽  
A Cell ◽  
Brain Ribosomes

scholarly journals Cell-free acylation of rat brain myelin proteolipid protein and DM-20

1987 ◽  
Vol 246 (3) ◽  
pp. 611-617 ◽  
Author(s):  
T Yoshimura ◽  
D Agrawal ◽  
H C Agrawal
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Palmitic Acid ◽  
Rat Brain ◽  
Polyacrylamide Gel Electrophoresis ◽  
Proteolipid Protein ◽  
Free System ◽  
Cell Free System ◽  
Selective Labelling ◽  
A Cell

Incubation of rat brain myelin with [3H]palmitic acid in the presence of ATP, CoA and MgCl2 or [14C]-palmitoyl-CoA in a cell-free system resulted in the selective labelling of ‘PLP’ [proteolipid protein; Folch & Lees (1951) J. Biol. Chem. 191, 807-817] and ‘DM-20’ [Agrawal, Burton, Fishman, Mitchell & Prensky (1972) J. Neurochem. 19, 2083-2089] which, after polyacrylamide-gel electrophoresis in SDS, were revealed by fluorography. These results provide evidence of the association of fatty acid-CoA ligase and acyltransferase in isolated myelin. Palmitic acid is covalently bound to PLP and DM-20, because 70 and 92% of the radioactivity was removed from proteolipid proteins after treatment with hydroxylamine and methanolic NaOH respectively. Incubation of myelin with [3H]palmitic acid in the absence of ATP, CoA, MgCl2, or all three, decreased incorporation of fatty acid into PLP to 3, 55, 18 and 2% respectively. The cell-free system exhibits specificity with respect to the chain length of the fatty acids, since myristic acid is incorporated into PLP at a lower rate when compared with palmitic and oleic acids. The acylation of PLP is an enzymic reaction, since (1) maximum incorporation of [3H]palmitic acid into PLP occurred at physiological temperatures and decreased with an increase in the temperature; (2) acylation of PLP with [3H]palmitic acid and [14C]palmitoyl-CoA was severely inhibited by SDS (0.05%); and (3) the incorporation of fatty acid and palmitoyl-CoA into PLP was substantially decreased by the process of freezing-thawing and freeze-drying of myelin. We have provided evidence that all of the enzymes required for acylation of PLP and DM-20 are present in isolated rat brain myelin. Acylation of PLP in a cell-free system with fatty acids and palmitoyl-CoA suggests that a presynthesized pool of non-acylated PLP and DM-20 is available for acylation.

scholarly journals Protein Synthesis in a Cell-free System from Rat Brain Sensitive to ACTH-like Peptides

1980 ◽  
Vol 34 (6) ◽  
pp. 1661-1670 ◽  
Author(s):  
P. Schotman ◽  
D. v. Heuven-Nolsen ◽  
W. H. Gispen
Keyword(s):  
Protein Synthesis ◽  
Rat Brain ◽  
Free System ◽  
Cell Free System ◽  
A Cell

scholarly journals The limiting factors of a cell-free protein-synthesizing system from rat brain

1970 ◽  
Vol 116 (1) ◽  
pp. 135-145 ◽  
Author(s):  
A. J. Dunn
Keyword(s):  
Rat Brain ◽  
Ribonucleic Acid ◽  
Limiting Factors ◽  
Contributory Factor ◽  
Free System ◽  
Chain Initiation ◽  
Cell Free System ◽  
Messenger Ribonucleic Acid ◽  
Low Concentrations ◽  
A Cell

The limiting factors of a cell-free system from rat brain for incorporating amino acids into protein were studied. The initial more rapid incorporation by microsomes, as opposed to that by ribosomes, is suggested to be due to damage of the ribosomes by detergent. The defect is rectifiable by incubation of the ribosomes in cell sap, so that ribosomes eventually incorporate more amino acid than do microsomes. This may be because ribonuclease, which is associated with the microsomes but removed by detergent treatment, inactivates the microsomal system. The factor that causes incorporation by microsomes to cease abruptly within 1h is not the lack of any precursor or of adenosine triphosphate, of the inactivation of cell-sap factors or the accumulation of inhibitory substances, but is a deficiency of usable messenger ribonucleic acid. Chain initiation in the system is negligible. Ribosomes also become jammed at the end of messenger ribonucleic acid molecules, unable to terminate protein chains. This eventually leads to jammed polyribosomes, which can be partially relieved by very low concentrations of puromycin. A study of the release of polypeptides synthesized in response to the addition of synthetic messengers did not provide any conclusive information on chain-termination sequences, but did indicate some phenomena that were artifacts. It is concluded that ribonuclease action is sufficient to account for all the deficiencies of the cell-free system, but a lack of chain initiation may be a contributory factor.

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