Biogenesis of 30-S subunits in exponentially growing Escherichia coli

Abstract 1. This study is designed to measure the rate of appearance of pulse-labeled ribosomal proteins onto 30-S subunits. Examination of individual 30-S ribosomal proteins fractionated by polyacrylamide gel electrophoresis indicates that the rate of appearance of the individual proteins varies during the chase period following a 1-min pulse with [ 14 C]leucine. A study of the individual 30-S ribosomal proteins labeled after a 15-sec pulse with [ 14 C]leucine and no additional incubation suggests that at least two groups of 30-S ribosomal proteins appear at different rates. Those proteins which appear most rapidly could be removed by treating the 30-S subunits with CsCl while most of the proteins which appear at the slower rate remain bound to the RNA.