Cytoplasmic extracts from Krebs II mouse ascites cells and from L cells translate messenger RNA from coliphage Qβ with fidelity to produce products that migrate on polyacrylamide gels with those products directed by Qβ RNA in an Escherichia coli cell-free system. The mammalian cell extracts correctly initiate and terminate Qβ coat protein synthesis, as shown by: ( i ) [ 3 H]lysine-and [ 3 H]arginine-labeled tryptic peptides derived from the coat-sized product resemble these from authentic Qβ coat protein, ( ii ) Qβ coat (which contains methionine only at the N-terminal end) can be radioactively labeled with methionine only if the methionine is formylated, and ( iii ) L cell extracts directed by Qβ am - 11 (an amber mutant in the coat protein) RNA make no completed coat-sized material, but do make a peptide the size of the authentic amber coat fragment.

Morrison, T. G., & Lodish, H. F. (1973). Translation of Bacteriophage Qβ RNA by Cytoplasmic Extracts of Mammalian Cells. Proceedings of the National Academy of Sciences, 70(2), 315–319.