Stronger affinity of reticulocyte release factor than natural suppressor tRNASer for the opal termination codon

FEBS Letters

Hitaka, Teruaki¹  Mizutani, Takaharu¹ 

[1] Faculty of Pharmaceutical Sciences, Nagoya City University, Mizuho-ku, Nagoya 467, Japan

关键词: Suppressor tRNA;    Release factor;    Seryl-tRNA;    Opal termination codon;    Reticulocyte lysate;   

DOI  :  10.1016/0014-5793(88)81428-5

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Animal natural suppressor tRNA did not affect the release reaction of reticulocyte release factor (RF) at the same concentration of tRNA (both estimated as being present at a similar level of 3–5 × 10⁻⁸ M in vivo); even at a 10-fold greater concentration the tRNA did not prevent the release reaction with RF. In order to confirm this result, the K _a values were determined. The K _a value between RF and UGA was 1.26 × 10⁶ M⁻¹ and that between the suppressor tRNA and UGA amounted to 8 × 10³ M⁻¹. This result showed that RF had a 150-fold stronger affinity than suppressor tRNA for the opal termination codon. Incorporation of phosphoserine into phosphoprotein via phosphoseryl-tRNA was inhibited by addition of RF to the reaction mixture. These results suggest that animal natural suppressor tRNA in the normal state does not perform its suppressor function, except in special cases where mRNA has the context structure near the opal termination codon (UGA).

【 授权许可】

Unknown