Dissociation of hepatic messenger ribonucleic acidS14 levels and nuclear transcriptional rates in suckling rats.

The messenger RNA (mRNA) coding for the rat hepatic protein spot 14(S14) (mol wt 17,000; pI 4.9) is rapidly responsive to T3 and carbohydrate administration in the adult animal. In 15-day-old suckling rats, the level of expression is 200-fold less than in 60-day-old chow-fed animals. However, the relative transcriptional activity of the S14 gene is only 30% higher in the 60-day-old rat than in the 15-day-old animal. Although T3 induces a 100-fold increase in mRNAS14 in 15-day-old animals, there was only a 17% increase in the S14 gene transcriptional activity. These results indicate that the hormonal and developmental regulation of the S14 gene in liver appears to be predominantly directed at the posttranscriptional level.