The Ribosome

This monograph is neither a historical outline of the development of the concepts of protein biosynthesis and the structure and functions of the ribosomes, nor an exhaustive survey of the literature on these questions. The monograph is based upon an analysis of the modern trends in this field. The purpose of the monograph was to formulate more or less generalized representations of the structure and" function of the ribosome, as we envision it at the present day. It may be that this attempt is premature for a number of reasons, and the concepts outlined here will very soon be revised. Nonetheless, despite this risk, we believe it to be advisable to undertake this attempt for the following reasons: firstly, the undertaken analysis could aid in the comprehension of the substantial mass of extremely scattered experimental data on the ribosomes presently available; secondly, in any event, even if most of the concepts outlined rapidly become obselete, they can still serve as a stimulus for a whole series of experiments; and thirdly, we hope that some of the concepts outlined will still remain essentially correct and relatively stable. In view of the aforementioned, we should make the following reservations. First of all, we made no attempt to cite all the literature on the problems discussed, but considered it sufficient to illustrate the various premises with one or several sample references.

Contenu

Fundamental Introduction.- 1. General Scheme of Protein Biosynthesis.- 2. Coding of Information (The Genetic Code).- 3. Storage and Replication of the Coded Information.- 4. Transfer of Information (Transcription).- 5. Involvement of Amino Acids in Protein Synthesis.- 6. Synthesis of Protein on the Ribosome (Translation).- One Structure of the Ribosome.- I. Physical Properties and Chemical Composition of the Ribosomes.- 1. Shape and Size.- 2. Compactness.- 3. Subdivision into Two Unequal Subparticles ("Subunits").- 4. Chemical Composition: RNA and Protein Content.- 5. Chemical Composition: Bound Low-Molecular Weight Cations.- 6. Summary.- II. Ribosomal RNA.- 1. Molecular Weight Characteristics.- 2. Continuity of Polynucleotide Chains.- 3. Nucleotide Composition.- 4. Nucleotide Sequence.- 5. Secondary Structure in Solution.- 6. Secondary Structure within the Ribosome.- III. Ribosomal Proteins.- 1. Definition.- 2. Number of Protein Molecules per Ribosome and Their Molecular Weight Characteristics.- 3. Amino Acid Composition and Sequence.- 4. Conformation.- 5. Intraribosomal Packing.- 6. Summary.- IV. Structural Transformations of Ribosomes.- 1. Reversible Dissociation-Association.- 2. Unfolding.- 3. Disassembly.- 4. Conformational Stability of Ribosomes.- 5. Some General Tentative Conclusions on the Quaternary Structure of the Ribosome.- Two Functioning of the Ribosome.- I. Components of the Protein-Synthesizing System.- 1. The Ribosome.- 2. The Template Polynucleotide.- 3 Aminoacyl-tRNA.- 4. GTP.- 5. "Transfer Factors" of Protein Nature.- 6. Protein "Initiation Factors".- 7. "Termination Factors".- 8. Inorganic Cations.- II. Association of the Ribosome with Components of the Protein-Synthesizing System.- 1. Association of the Ribosome with the Template Polynucleotide.- 2. Formation of a Ternary Complex Ribosome - Template - AminoacyltRNA.- 3. Association of the Ribosome with tRNA in the Absence of a Template.- 4. Specific Stimulation of the Binding of Peptidyl-tRNA to the Ribosome by the Template.- III. Stages of Translation.- 1. Formation of the Initial Complex Ribosome - Template - (Aminoacyl-tRNA)2 and Initiation of Translation.- 2. Translation Proper ("Polymerization of Amino Acid Residues").- 3. Termination of Translation.- 4. On the Intercistronic Punctuation in Polycistronic Mrna's.- IV. Appendix: On the Mechanism of the Action of Certain Antibiotics.- 1. Puromycin.- 2. Chloramphenicol (Chloromycetin).- 3. Tetracyclines.- 4. Streptomycin and Other Aminoglucoside Antibiotics.- References.