Stop is not the end: physiological implications of translational readthrough.

The translational readthrough mechanism permits the occasional misreading of termination codons by normal charged tRNAs causing extended translation beyond the stop signal. In both prokaryotes and eukaryotes translational readthrough is involved in the regulation of gene expression, as for example in the synthesis of the enzyme reverse transcriptase of the Murine Leukemia Virus (MuLV) (Yoshinaka et al., 1985). Here we particularly deal with the sensitivity of the translational readthrough process to two parameters which are affected by changes in physiological conditions: (1) fluctuations in the concentration of readthrough tRNAs and (b) The affinity of the tRNAs to termination codons. We also discuss the possible role of translational readthrough during major changes in cell physiology.