RIBOSOMAL PROTEIN POOLS AND ASSEMBLY OF RIBOSOMES IN ESCHERICHIA COLI

Bacterial ribosomal proteins are known to accumulate in soluble pools prior to their entry into ribosomes. An evaluation of the size of individual ribosomal protein pools has been performed using pulse-labeling and chase experiments, followed by determination of the amount of radioactivity incorporated into the purified proteins. Additionally, the incorporation of labeled proteins into immature ribosomes or into complete ribosomes has been studied for short periods of time. The results indicate that: (1) ribosomal protein pools are heterogeneous in size. (2) There is unequal labeling of the proteins in the mature ribosomes. This is compatible with the proposal that the entry of proteins from the soluble pools into ribosomes proceeds with a definite order and at a specific rate. © 1969, American Chemical Society. All rights reserved.