Effect of concentration of potassium salts on the activity of the N-ethylmaleimide-treated hemin-controlled translational inhibitor.
The effect of various concentrations of potassium salts on the activity of the N-ethylmaleimide(NEM)-treated hemin-controlled translational inhibitor (HCI) was investigated using the rabbit reticulocyte lysate system. The NEM-treated HCI was found to be less active for the inhibition of globin synthesis at higher concentrations of potassium salts. In addition, the binding of [35S]Met-tRNAf to the 40S ribosomal subunits was inhibited more profoundly at 100 mM than at 240 mM KOAc. The phosphorylation of the NEM-treated HCI and eukaryotic initiation factor, eIF-2, was studied at various concentrations of KOAc. The NEM-treated HCI was phosphorylated to an almost constant extent at 20 to 300 mM K+, but the phosphorylation of eIF-2 alpha by the inhibitor decreased with increasing concentration of KOAc. It was also found that the incubation of the 32P-labeled inhibitor with eIF-2 did not produce the 32P-labeled eIF-2. In the light of these data, a possible relationship between the phosphorylation of the inhibitor or eIF-2 alpha and the inhibition of globin synthesis by the inhibitor is discussed.
D000818:Animals; D001665:Binding Sites / Q000187:drug effects; D005033:Ethylmaleimide / Q000494:pharmacology*; D015852:Eukaryotic Initiation Factor-2; D006418:Heme / Q000031:analogs & derivatives*; D006427:Hemin / Q000378:metabolism*; D009994:Osmolar Concentration; D010448:Peptide Initiation Factors / Q000378:metabolism; D010766:Phosphorylation; D011188:Potassium / Q000494:pharmacology*; D014176:Protein Biosynthesis; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D012335:RNA, Ribosomal / Q000378:metabolism; D011817:Rabbits; D012156:Reticulocytes / Q000378:metabolism*; D019892:eIF-2 Kinase
D015852:Eukaryotic Initiation Factor-2; D010448:Peptide Initiation Factors; D012335:RNA, Ribosomal; D006418:Heme; D006427:Hemin; D017346:Protein Serine-Threonine Kinases; D019892:eIF-2 Kinase; D005033:Ethylmaleimide; D011188:Potassium