Translational Stability of Native and Deadenylylated Rabbit Globin mRNA Injected into HeLa Cells

HeLa human cells were injected with a natural mixture of rabbit α and β globin mRNA. They were incubated for 6 hr with [35S]methionine either immediately after injection or 20 hr later. The labeled proteins in the injected cells were analyzed by fluorography of two-dimensional electrophoresis gels. By using this procedure, it was possible to show that, during the first few hours after injection, both α and β globin molecules are synthesized with an α to β ratio approximately equal to 0.6. The rate of synthesis of α globin decreased significantly faster than that of β globin over a 26-hr period after injection of the two mRNAs. It thus seems that two messenger RNAs coding for closely related polypeptides possess a markedly different translational stability. When deadenylylated rabbit globin mRNAs were injected into HeLa cells, no globin synthesis could be detected by the techniques used. We conclude that the translational half-life of mRNAs lacking poly(A) is very short in these cells. It is thus clear that the poly(A) segment is required to ensure stability to globin mRNA in somatic cells as in Xenopus oocytes.