Decreased initiation factor activity in mouse L cells treated with interferon

Abstract

INHIBITION of virus-directed protein synthesising events in extracts of cells treated with interferon has been reported^1–3. Inhibition of translation of viral mRNAs has been associated with a protein bound to ribosomes of cells treated with interferon^4,5. This inhibition may involve the initiation or elongation steps in protein synthesis^6,7. Recently, initiation factors for protein synthesis have been isolated from a variety of eukaryotic cells, and it has been established that the initiation factors interact with non-formylated methionyl initiator RNA (Met-tRNA_f) and GTP to form a ternary complex^8,9. The experiments presented here show that the activity of initiation factor(s) to form a ternary complex may be impaired or altered in mouse L cells treated with homologous interferon. In preliminary experiments with the initiation factor preparation it was confirmed that the formation of a ternary complex (Met-tRNA_f–elF‐GTP) required GTP for maximal formation (within 2 min at 37 C) and the amount of complex formed was directly proportional to the concentration of initiation factor (Fig. 1). ATP did not substitute for GTP and Mg²⁺ inhibited its formation (data not shown).