Variation of ribosomal proteins with bacterial growth rate.

The composition of ribosomal proteins has been examined as a function of the growth rate of Escherichia coli cells. Seven sets of cultural conditions, utilizing different combinations of carbon and nitrogen sources, were employed to provide a 36-fold spread in growth rate. The cellular content of most of the ribosomal proteins in ribosomes decreased to a similar extent in the very slow-growing cultures. Major exceptions were proteins S6 and L12, which exhibited a much more pronounced decrease , and S21, which exhibited an increase. None of the proteins remained invariant with growth rate.