The Process of Translation: A Bird’s-eye View

Abstract

INTRODUCTION: SURVEY OF PROTEIN SYNTHESIS
Ribosomes function in protein synthesis and the complexity of ribosome structure can be accounted for by the complexity of this process. This is why a short survey of protein synthesis is presented here. Aspects of ribosome structure and function discussed in detail in other chapters of this book are deemphasized. To make the reading smoother and to save space, with some exceptions, only recent references are provided. The missing references can be obtained from the more detailed reviews devoted to this topic in recent years (e.g., Lengyel and Soil 1969; Lucas-Lenard and Lipmann 1971; Kozak and Nathans 1972; Haselkorn and Rothman-Denes 1973). A collection of papers on protein synthesis can be found in the Cold Spring Harbor Symposium, Volume 34 (1969). A collection of reviews on various aspects of this process was edited by L. Bosch (1972).

Messenger RNA and Cell-Free Systems
The ribosome is the most complex component of the protein synthesizing machinery of the cell. This machinery translates the information provided in the form of nucleotide sequences in mRNAs into polypeptides. The mRNAs are read in the 5′ to 3′ direction and the polypeptides are synthesized from the amino-terminal towards the carboxy-terminal amino acid. Messenger RNAs contain (a) sequences which are not translated and (b) sequences specifying initiation of translation (initiation signals); these are followed by (c) sequences that are actually translated and which in turn are followed by (d) sequences specifying the termination of translation (termination signals), which are not translated (Weissmann...