| Abstract: | The mode of distribution of labelled amino acids between the nascent and completed polypeptides during incubation of rat liver mitochondria in vitro was studied. This distribution corresponds to protein synthesis of uneven type with a sharp deceleration (pause) during the translation of the middle part of mRNA. The correspondence manifests itself in the fact that i) regular increment of radioactivity of nascent and completed polypeptides in coupled mitochondria was observed in interval less then ts (time necessary for the synthesis of an average polypeptide), and, ii) serine hydroxamate or norleucine have much less effect on the labelling of total protein as well as on the duration of synthesis of an average polypeptide, as could be expected from their inhibition of unmasked elongation. The duration of an expected pause during translation might exceed 4-fold the time necessary for elongation of the largest part of the polypeptide. |
