| Abstract
| - The effect of concentration of KCl, magnesium acetate (MgAc) and spermine on the translation of rabbit globin mRNAs was studied by using the rabbit reticulocyte lysate system. Globin synthesis was studied by using L[U-14C]leucine or L-f[35S]Met-tRNAfMet The optimum concentrations of MgAc and KCl were 1.4-2.5 m and 70 mM respectively. Spermine stimulated rabbit globin synthesis at relatively low concentrations of MgAc, but inhibited it at relatively high concentrations of MgAc. High α/β synthetic ratios were observed at low concentrations of KCl and MgAc, but low α/β synthetic ratios were observed at high concentrations of KCl and MgAc. Spermine decreased the α/β synthetic ratios at relatively low concentrations of MgAc. Nascent chains labelled with f[35S] were released at various concentrations of KCl, MgAc, and spermine in the lysate system. Release of the nascent chains was inhibited at low concentrations of KCl, but almost 90% of the nascent chains were released at 70-120 m KCl. The release of the nascent chains was maximum around optimum concentrations of MgAc, but inhibited at other concentrations. Spermine stimulated the release of the nascent chains. The analyses of the released chains showed that the ratio of f[35S]Met-α to f[35S]Met-β globin chains was almost constant at various concentrations of KCl, MgAc, and spermine. Nascent chains were labelled with f[35S]Met at various concentrations of KCl, MgAc, and spermine. The labelled nascent chains were released in the incubation mixture under the optimum conditions. The analyses of the released chains showed that the ratio of f[35S]Met-α to f[35S]Met-β was similar to the α/β synthetic ratios obtained at various concentrations of KCl, MgAc, and spermine. The data presented above suggest that changes in the α/β synthetic ratio with added KCl, MgAc, and spermine were due to changes in the rates of the translational initiation of α and β globin mRNAs.
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