Inhibition of globin synthesis by rabbit reticulocyte rRNAs.

The effect of concentration of rabbit reticulocyte rRNAs on the translation of rabbit globin mRNAs was studied by using a rabbit reticulocyte lysate system. Globin synthesis was studied using L-[U-14C]leucine. Both the 18S and 28S rRNA inhibited globin synthesis. The 18S rRNA inhibited the synthesis of alpha-globin chain more than that of beta chain, but the 28S rRNA inhibited the synthesis of alpha- and beta-chains almost equally. Nascent chains prelabelled with [14C]Leu or f[35S]Met were released at various concentrations of rRNAs. Release of the nascent chains was not inhibited at various concentrations of rRNAs. The ratios [14C]alpha/[14C]beta and [35S]alpha/[35S]beta in the released chains were almost constant at various concentrations of rRNAs. It therefore appears that the inhibition of globin synthesis by these rRNAs was at the step of initiation.