The Eukaryotic Ribosome

Contents References 11 II. A short historical survey 13 References 16 III. Ribosomes within the cell 20 1. Proportion of ribosomes in tissues 21 2. Free and membrane-bound ribo- mes 22 3. Ribosomes in nucleoli 26 4. Structure of polysomes in the cell 26 5. Ribosomal crystals 33 6. References 33 IV. Some general properties of ribosomes 41 1. Physical characteristics 41 2. Chemical characteristics 43 3. References 44 V. Morphology of ribosomes and poly somes 47 1. Electron microscopy 47 a) The small ribosomal subunit 48 b) The large ribosomal subunit 48 c) The monomeric ribosome 52 d) Three-dimensional models 54 e) Polysomes 55 2. Small-angle X-ray scattering 55 a) The monomeric ribosome 56 b) Polysomes 57 3. References 57 VI. Chemical components 61 1. Ribosomal proteins 61 a) Electrophoretic separation and num ber 61 b) Preparation of single ribosomal pro teins 67 c) Molecular weights 68 d) Amino acid composition and amino acid sequences 71 e) Stoichiometry 71 f) Posttranslational modifications 72 g) Comparison of ribosomal proteins of different tissues 73 h) Species specificities and evolution 74 i) Ribosomal proteins of mitochondria and chloroplasts 75 k) Ribosomal mutants with altered pro teins 75 5 3. Formation of preribosomal 2. Phosphorylation of ribosomal prote particles 139 ins 76 4. References 141 a) In vitro phosphorylation and de phosphorylation 76 VIII. Dissociation - reassociation processes b) In vivo phosphorylation 77 of ribosomal particles 151 c) Phosphorylation of ribosomal pro tein S 6 78 1.

I. Introduction.- References.- A short historical survey.- References.- III. Ribosomes within the cell.- 1. Proportion of ribosomes in tissues.- 2. Free and membrane-bound ribosomes.- 3. Ribosomes in nucleoli.- 4. Structure of polysomes in the cell.- 5. Ribosomal crystals.- 6. References.- IV. Some general properties of ribosomes.- 1. Physical characteristics.- 2. Chemical characteristics.- 3. References.- V. Morphology of ribosomes and polysomes.- 1. Electron microscopy.- a) The small ribosomal subunit.- b) The large ribosomal subunit.- c) The monomeric ribosome.- d) Three-dimensional models.- e) Polysomes.- 2. Small-angle X-ray scattering.- a) The monomeric ribosome.- b) Polysomes.- 3. References.- VI. Chemical components.- 1. Ribosomal proteins.- a) Electrophoretic separation and number.- b) Preparation of single ribosomal proteins.- c) Molecular weights.- d) Amino acid composition and amino acid sequences.- e) Stoichiometry.- f) Posttranslational modifications.- g) Comparison of ribosomal proteins of different tissues.- h) Species specificities and evolution.- i) Ribosomal proteins of mitochondria and chloroplasts.- k) Ribosomal mutants with altered proteins.- 2. Phosphorylation of ribosomal proteins.- a) In vitro phosphorylation and de-phosphorylation.- b) In vivo phosphorylation.- c) Phosphorylation of ribosomal protein S 6.- d) Acidic ribosomal phosphoproteins.- 3. Immunochemical properties of ribosomal particles and proteins.- a) Applicability of antibodies.- b) Antigenicity of 80 S ribosomes and their total proteins.- c) Antigenicity of 40 S and 60 S ribosomal subunits.- d) Immunological properties of purified individual proteins.- e) Antibodies to ribosomes in sera of patients with SLE.- 4. Ribosomal ribonucleic acids.- a) High molecular weight ribosomal ribonucleic acids.- Molecular weights.- Base composition.- Sequences.- Secondary structure.- b) Low molecular weight ribosomal ribonucleic acids.- 5 S RNA.- 5.8 S RNA.- 5. Proteolytic and nucleolytic activities of ribosomal particles.- 6. Other components.- 7. References.- VII. Biosynthesis of ribosomal components and biogenesis of ribosomal particles.- 1. Ribosomal RNA.- a) Primary pre-rRNA.- b) 5' ? 3'polarity of the pre-rRNA molecule.- c) Methylation and pseudouridylation of pre-rRNA.- d) Processing of pre-rRNA.- e) Biosynthesis of 5 S rRNA.- 2. Ribosomal proteins.- 3. Formation of preribosomal particles.- 4. References.- VIII. Dissociation-reassociation processes of ribosomal particles.- 1. Dissociation by withdrawal of magnesium.- 2. Other agents for dissociating eukaryotic ribosomes.- 3. Preparation of ribosomal subunits re-associable to active ribosomes.- 4. Reassociation of ribosomal subunits.- 5. Native ribosomal subunits.- 6. References.- IX. Interaction, topography and function of ribosomal components.- 1. Interactions of proteins and RNA.- 2. Topography of proteins and RNA within the ribosome.- a) Chemical substitution of proteins in ribosomal particles.- b) Enzymatic degradation of proteins and RNA in ribosomal particles.- c) In vitro phosphorylation of proteins in ribosomal particles.- d) Cross-linking of proteins within ribosomal subunits.- e) Localization of ribosomal proteins by immune electron microscopy.- 3. Functions of ribosomal proteins.- a) Functions of ribosomal split proteins.- b) Analysis of functions of ribosomal proteins by chemical substitution.- c) Affinity labeling.- d) Interactions between the small ribosomal subunit and initiation factors.- e) Ribosomal proteins involved in antibiotic resistance and lectin binding.- 4. Functions of ribosomal ribonucleic acids.- 5. References.- X. Interactions of ribosomes with membranes.- 1. Activity of free and membrane-bound polysomes.- 2. Dynamics of ribosomal subunits between free and membrane-bound polysomes.- a) RNA labeling experiments.- b) Reassociation experiments.- 3. Chemical properties of free and mem-brane-bound ribosomes.- a) Ribosomal RNA.- b) Ribosomal proteins.- 4. Components and mechanisms involved in binding of ribosomes to membranes.- a) The role of ribosomal subunits.- b) The role of membrane components.- c) The role of ionic forces and the nascent peptide chain.- d) The role of messenger-RNA.- e) The action of inhibitors of protein synthesis on ribosome-membrane interactions.- 5. Vectorial discharge of polypeptide chains from membrane-bound polysomes.- 6. References.- XI. Function of eukaryotic ribosomes.- 1. Nonribosomal components of the protein synthesizing system.- a) Messenger-RNA.- b) Transfer-RNA.- c) Initiation factors.- d) Elongation factors.- e) Role of GTP during elongation.- f) Termination factors.- g) Dissociation factors.- 2. The process of eukaryotic protein synthesis.- a) Initiation.- b) Elongation.- c) Termination.- 3. Protein synthesis on membrane-bound ribosomes.- 4. Some regulatory aspects of protein biosynthesis in eukaryotes.- a) Hemin control of protein synthesis in reticulocytes.- b) Action of interferon on protein synthesis.- c) Shut-off of protein synthesis after viral infection.- 5. References.- XII. Aphoristic synopsis and outlook.- XIII. Notes added in proof.- XIV. Subject index.- XV. Reference index.