Insulin affects only initiation and not elongation in protein synthesis in soleus muscles of lean and obese mice.

The effect of insulin on polypeptide chain initiation and elongation has been studied in soleus muscles isolated from lean and goldthioglucose-obese mice. Insulin increased the amount of radioactivity present in nascent chains by approximately 30% in muscles from both lean and obese mice, indicating that it stimulates peptide chain initiation. In contrast, elongation rates, estimated by measurement of half transit time, were similar in basal conditions and insulin-treated muscles of lean and obese animals. Thus, insulin increased the initiation without modifying the elongation rates. Obesity did not affect either basal rates of initiation and elongation or the effect of insulin.