RIBOSOMAL PROTEINS: STRUCTURE, FUNCTION, AND EVOLUTI
The question about the reason for the variety of ribosomal proteins that arose more than 40 years ago is still open. Ribosomes of modern organisms contain 50-80 individual proteins. Some of them are conserved in all domains of life (universal ribosomal proteins) while other are a feature of Bacteria, Archaea, or Eukaryota. Extensive information about ribosomal proteins has been obtained since that time. However, the role of the majority of ribosomal proteins in the formation and functioning of the ribosome is still not so clear. In the present review, a comprehensive evalua# tion of structural conservatism of ribosomal proteins from evolutionarily distant organisms is made on the basis of recent experimental and bioinformatic data. Accounting for current knowledge of the features of the structural orga# nization of the universal proteins and their intermolecular contacts, a possible role of individual proteins and their structural elements in the ribosome formation and functioning is discussed. The structural and functional conser# vatism of most proteins of this group suggests that they would be already present in the ribosome in the early steps of its evolution.