snRNP’s and scRNP’s in Eukaryotic Cells (With 4 Figures).- A. Historical Background.- B. The U snRNA’s.- C. Other Small RNA’s Precipitable with Autoimmune Antibodies.- D. Other Small RNP’s of Organized Function.- E. Concluding Remarks.- References.- Nucleotide-specific Ribonucleases from Eukaryotes. Their Possible Roles During Poly (A) (+) mRNA Maturation and Degradation (With 12 Figures).- A. Introduction.- B. Posttranscriptional Events in mRNA Maturation.- C. Eukaryotic Ribonucleases: a Brief Survey.- D. Poly (A) Metabolism.- E. Splicing.- F. Role of Poly (A) Chain Length Controlled by Specific Nucleases and of snRNP’s During Poly (A) (+) mRNA-nuclear Matrix Association and Nucleocytoplasmic Poly (A) (+) mRNA Transport.- G. Conclusion and Future Directions.- References.- The Cap Structure of Eukaryotic Messenger RNA and its Interaction with Cap-binding Protein (With 12 Figures).- A. Introduction.- B. 5’ —Terminal Cap Structure of Messenger RNA.- C. The Dependence of Translation on the Cap Structure.- D. Identification of the Cap-binding Protein.- E. Involvement of Cap-binding Proteins in Initiation of Protein Synthesis.- F. Antibodies to Cap-binding Protein-related Polypeptides..- G. Effect of Virus Infection on Cap-binding Protein.- H. Cap-binding Protein and the Cytoskeleton.- I. Conclusion and Future Directions.- K. 1984 Addendum.- References.- Cell-Cell Recognition in Lower Multicellular Eukaryotes. Models Supporting the Modulation Theory of Adhesion (With 9 Figures).- A. Introduction.- B. Cell-Cell Adhesion in Vertebrates.- C. Cell Adhesion Molecules in Sponges.- D. Cell Recognition Molecules in Corals.- E. Conclusion.- References.