The role of SH-groups of human ribosomal subunits in polypeptide synthesis

The SH-group(s) present in the 60S subunit were shown to play a significant role in the poly U-dependent binding of Phe-tRNA^∗ to 80S ribosomes. 60S subunits preincubated with NEM and assayed with untreated 40S subunits gave only 17% of the normal activity in the non-enzymatic binding of Phe-tRNA and 35% of the normal activity in poly Phe synthesis. NEM-treated 40S plus untreated 60S subunits, however, displayed 77% activity in non-enzymatic binding and 95% activity in poly Phe synthesis.