STUDIES ON THE COMPOSITION OF THE PROTEIN FROM ESCHERICHIA COLI RIBOSOMES

Publisher Website
Google Scholar
Abstract
NH2-terminal group analyses on E. coli ribosomal protein indicate the presence of 2 major end groups methionine and alanine. The results are consistent with the view that ribosomal protein is not a random sample of total cellular protein but, on the contrary, a class of basic proteins which quite possibly serves the role of maintaining ribosomal RNA in suitable configuration for protein synthesis. The constituent protein chains of ribosomes, with an average molecular weight of 25,000, thus fall into 2 major classes: those chains with methionine as NH2-terminal residue and those with alanine. From the results of fractionation experiments, it is further apparent that within each of these 2 major classes not all chains are chemically identical. The extent and significance of the chemical differences between chains possessing the same NH2-terminal residue are now being investigated. It is of interest to note that, in this respect, E. coli ribosomal protein bears a striking resemblance to calf thymus histone, where a simple amino end group picture (with alanine and proline accounting for over 90% of the end groups) is likewise accompanied by a complex protein composition.