RNA turnover in endoplasmic reticulum-bound and free ribosomes

The turnover of RNA in endoplasmic-bound and free ribosomes of rat liver and kidney was measured following the loss of radioactivity as supplied by [14C]orotic acid. Both fractions showed a single exponential decay pattern and a half-life of about 6 days. It can be concluded from the data that the relationship between ribosomes and endoplasmic reticulum is dynamic.