Association of a cyclic AMP-dependent protein kinase with a purified translational inhibitor isolated from hemin-deficient rabbit reticulocyte lysates.

Abstract

In the absence of added hemin, protein synthesis in rabbit reticulocyte lysates proceeds at maximal linear rates for several minutes and then ceases abruptly. Inhibition involves the action of a translational inhibitor whose formation is regulated by hemin. Addition of the isolated inhibitor to hemin-supplemented lysates produces an inhibition of protein chain initiation similar to that observed in heme-deficiency. The inhibitor has been purified over 300-fold and contains a protein kinase activity that copurifies with the inhibitory function. With calf thymus histone II as the phosphate receptor, the inhibitor-associated protein kinase requires ATP as the phosphorylating agent. Cyclic AMP stimulates kinase activity 5-to 8-fold; the concentration of cyclic AMP required for half-maximal activity is 4 'X 10-8 M. Preincubation of the inhibitor in the presence of cyclic AMP significantly reduces cyclic AMP-dependent phosphorylation and inhibitory activity. The corresponding protein' kinase activity from hemin-supplemented lysates displays reduced cyclic AMP-dependency and little or no inhibitory'activity.These findings suggest that the protein kinase activity associated with the purified translational inhibitor is involved in

Regeneration of renal proximal tubules after mercuric chloride injury is accompanied by increased binding of aminoacyl-transfer ribonucleic acid

“…For regenerating liver and liver during microsomalenzyme induction, evidence has been obtained for a decrease in the activity of an inhibitor of aminoacyltRNA binding (Goodchild & Nicholls, 1976;Tominaga et al, 1975), as well as an increase in the activity of elongation factor 1 (Cappon & Nicholls, 1974a (Petryshyn & Nicholls, 1976). Further, the absence of a differential effect on initiation suggests that changes in an inhibitor affecting initiation, such as reported for tissues other than kidney, cannot account for the results reported here (Gross & Rabinowitz, 1972;Lodish & Desalu, 1973;Levin et al, 1975;Bester et al, 1975). The increased incorporation with the supernatant fraction of regenerating kidneys could not be attributed to the amount of mRNA in the preparation, since the increase was present when excess of poly(U) directed the peptide formation as well as when endogenous mRNA in the control-liver ribosome preparation directed incorporation.…”

Interferon, double-stranded RNA, and protein phosphorylation.

“…The reaction mixtures were incubated without (10,12) or with 1.5 ,g/ml of ds reo RNA (11,13). The extracts added to the reaction mixtures in (D) were from cells treated with DEAEdextran (14,15) or cells treated with DEAE-dextran and the interferon inducer poly(I)-poly(C) (16,17). The reaction mixtures were incubated without (14,16) or with 1.5 Mg/ml of ds reo RNA (15,17).…”

Interferon-induced inhibition of protein synthesis in L-cell extracts: an ATP-dependent step in the activation of an inhibitor by double-stranded RNA.

“…Balkow, T. Hunt, and R. J. Jackson, personal communication). Protein kinase activity has also been found associated with a partially purified inhibitor of protein synthesis from reticulocytes (13). It may be that a similar mechanism is involved in the interferon-mediated inhibition.…”