Main description:

Biological functions are almost exclusively attributed to macromolecules, i.e. nucleic acids, proteins and polysaccharides. To gain their complete functional activities these biomolecules have to associate with the nuclear matrix, the cytoskeleton and the cell/plasma membranes. It is the aim of this series to discuss actual aspects in the field of structure-associated genetic and epigenetic functional processes. This series of survey reviews fills the gap in structure-associated information flow, and is a vital reference work for scientists in molecular and cell biology.

Contents:

Association of DNA with Nuclear Matrix.- A. Introduction.- B. MAR Elements and Their Properties.- C. Roles of MAR Elements in DNA Packaging and DNA Replication.- References.- Nuclear Import in Vitro.- A. Overview of Nuclear Import.- I. Nuclear Import Occurs Through the Nuclear Pore.- II. The Structure and Composition of the Nuclear Pore.- III. Functional Properties of the Nuclear Pore.- IV. Signals for Nuclear Accumulation.- V. The Effect of Multiple Nuclear Targeting Signals in a Protein.- VI. Is There a Role for Intranuclear Binding in Nuclear Import?.- VII. Nuclear Import is an Active Process. Evidence for a Signal Sequence Receptor.- VIII. Is the Signal Sequence Receptor Heterogeneous?.- IX. Regulation of Nuclear Import.- 1. Changes in Nuclear/Cytoplasmic Localization During Embryogenesis.- 2. Nuclear Import of snRNP Particles.- 3. Nuclear Exclusion of Transcription and Replication Factors: a Regulatory Mechanism?.- 4. Reversible Nucleocytoplasmic Movement.- 5. Nuclear Import of Hormone Receptors: Hormone-Dependent?.- B. In Vitro Systems for Studying Nuclear Import.- I. In Vitro Systems Based on Xenopus Egg Extracts.- 1. Rationale for the Use of Egg Extracts.- 2. Nuclear Import Activity in Egg Extracts is Authentic.- 3. Nuclear Import is Inhibited by the Lectin, Wheat Germ Agglutinin. Are Nuclear Pore Glycoproteins Involved in the Transport Mechanism?.- 4. Nuclear Import is Separable Experimentally into Two Steps: Signal-Mediated Binding and ATP-Dependent Translocation.- II. In Vitro Systems Based on Isolated Nuclei in Buffers.- 1. Heparin-Extracted Nuclei.- 2. Systems Involving Whole Isolated Nuclei in Defined Buffers.- III. Passive Influx into Isolated Nuclei.- C. Conclusion.- References.- Cytoplasmic Assembly and Nuclear Transport of the snRNP Particles.- A. Introduction.- B. Maturation of the snRNAs.- I. snRNAs Appear Transiently in the Cytoplasm.- II. 3' End Processing of snRNAs.- III. Nucleotide Modification Including the 5' Cap.- C. snRNP Particle Assembly.- I. snRNP Proteins.- II. snRNP Core Protein Assembly.- III. Relationship of B, B', and N snRNP Core Proteins.- IV. U1 and U2 Specific Proteins.- V. Independent Synthesis and Assembly of snRNP Proteins in Xenopus Oocytes.- VI. In Vitro Assembly of snRNP Particles.- VII. U6 snRNP.- D. Nuclear Accumulation of snRNP Particles.- I. Interphase.- 1. snRNP Core Particles.- 2. snRNP Specific Proteins.- II. Mitosis.- E. Summary and Perspectives.- References.- The Centrosome: Recent Advances on Structure and Functions.- A. Definitions.- B. Isolation of Centrosomes from Somatic Cells.- C. The Structure of Isolated Centrosomes.- D. Centrosomal Proteins.- E. The Centrosome and the Nucleation of Microtubules.- F. The Centrosome Cycle in the Cell Cycle.- G. Centrosome Continuity.- H. Centrosome and the Spindle Formation.- I. Centrosome and the Spatial Organization of Microtubules in Terminally Differentiated Cells.- J. Centrosome and Cell Polarity/Movement.- K. Conclusion.- References.- Role of Nonsense, Frameshift, and Missense Suppressor tRNAs in Mammalian Cells.- A. Introduction.- B. Suppression of Nonsense Codons.- I. Naturally Occurring Nonsense Suppressor tRNAs.- 1. Amber Suppressor tRNAs.- 2. Ochre Suppressor tRNAs.- 3. Opal Suppressor tRNAs.- II. Assays for Nonsense Suppressor tRNAs and Nonsense Mutations.- III. Introduction of Nonsense Suppressor tRNA Genes into Intact Cells.- IV. Other Considerations.- C. Ribosomal Frameshifting.- I. Ribosomal Frameshifting in Retroviruses.- II. tRNAs Involved in Frameshifting.- D. Missense Suppression and Misrecognition of Genetic Codewords.- E. Conclusion.- References.- UAG Suppressor Glutamine tRNA in Uninfected and Retrovirus-Infected Mammalian Cells.- A. Introduction.- B. Isolation and Sequence Analysis of Glutamine tRNA from Mammalian Cells.- C. Analysis of Suppressor Activity of Mammalian Glutamine tRNA.- D. Selective Increase of Suppressor Glutamine tRNA in Retrovirus-Infected Cells.- E. Influence of Increased Amount of Suppressor tRNA on Translation Reaction of Cellular mRNA.- F. Discussion.- References.- Essential Genes for Development of Dictyostelium.- A. Introduction.- B. Genetic Analysis in Dictyostelium.- C. Temporal Sequence of Differentiations.- D. Initiation of Development.- E. Stage 1: Chemotaxis.- F. cAMP Regulation of Transcription and Chemotaxis.- G. Stage 2: Integration.- H. Stage 3: Divergence.- I. Stage 4: Culmination.- J. Dependent Sequence.- References.