he past fifteen years have seen tremendous growth in our understanding of T the many post-transcriptional processing steps involved in producing func tional eukaryotic mRNA from primary gene transcripts (pre-mRNA). New processing reactions, such as splicing and RNA editing, have been discovered and detailed biochemical and genetic studies continue to yield important new insights into the reaction mechanisms and molecular interactions involved. It is now apparent that regulation of RNA processing plays a significant role in the control of gene expression and development. An increased understanding of RNA processing mechanisms has also proved to be of considerable clinical importance in the pathology of inherited disease and viral infection. This volume seeks to review the rapid progress being made in the study of how mRNA precursors are processed into mRNA and to convey the broad scope of the RNA field and its relevance to other areas of cell biology and medicine. Since one of the major themes of RNA processing is the recognition of specific RNA sequences and structures by protein factors, we begin with reviews of RNA-protein interactions. In chapter 1 David Lilley presents an overview of RNA structure and illustrates how the structural features of RNA molecules are exploited for specific recognition by protein, while in chapter 2 Maurice Swanson discusses the structure and function of the large family of hnRNP proteins that bind to pre-mRNA. The next four chapters focus on pre-mRNA splicing.

Providing a guide to classical experimental approaches to decipher splicing mechanisms and experimental strategies that rely on novel multi-disciplinary approaches, Spliceosomal Pre-mRNA Splicing: Methods and Protocols describes the theory of alternative pre-mRNA splicing in seven introductory chapters and then introduces protocols and their theoretical background relevant for a variety of experimental research. These protocol chapters cover basic methods to detect splicing events, analyses of alternative pre-mRNA splicing in vitro and in vivo manipulation of splicing events and high-throughput and bioinformatic analyses of alternative splicing. Written in the highly successful Methods in Molecular Biology series format, chapters include introductions to their respective topics, lists of the necessary materials and reagents, step-by-step, readily reproducible protocols and tips on troubleshooting and avoiding known pitfalls. Comprehensive and practical, Spliceosomal Pre-mRNA Splicing: Methods and Protocols will aid newcomers and seasoned molecular biologists in understanding the fascinating world of alternative splicing with the ultimate goal of paving the way for many new discoveries to come.

This volume focuses on the major aspects of post-transcriptional mRNA processing in the nucleus of eukaryotic cells. Each of the described mRNA reactions is required for proper gene expression and can also serve as a control point for regulating the expression of many genes, for example duringembryonic development or in different cell types. The different chapters review the assembly of newly synthesized nuclear mRNA transcripts into hnRNP particles and catalytically active spliceosomes; the structure and mechanism of action of small nuclear ribonucleoprotein particles and proteinfactors that catalyse pre-mRNA splicing in mammalian cells and in yeast; the regulation of gene expression and generation of protein isoform diversity by alternative splicing; the mechanisms of 3' end cleavage and polyadenylation; the architecture of the cell nucleus in relation to these processesand to the localization of the relevant substrates and factors; the diverse mechanisms of RNA processing by ribozymes and their potential relevance for nuclear mRNA processing; the mechanism of spliced-leader addition by trans-splicing in nematodes and trypanosomes; and the process ofinsertion/deletion mRNA editing in kinetoplasmid protozoa. In each chapter, leading researchers have provided detailed, critical reviews of the history, experimental approaches, major advances, current ideas and models, as well as future directions, for each of these active areas of research.

The discovery in 1977 that genes are split into exons and introns has done away with the one gene - one protein dogma. Indeed, the removal of introns from the primary RNA transcript is not necessarily straightforward since there may be optional pathways leading to different messenger RNAs and consequently to different proteins. Examples of such an alternative splicing mechanism cover all fields of biology. Moreover, there are plenty of occurrences where deviant splicing can have pathological effects. Despite the high number of specific cases of alternative splicing, it was not until recently that the generality and extent of this phenomenon was fully appreciated. A superficial reading of the preliminary sequence of the human genome published in 2001 led to the surprising, and even deceiving to many scientists, low number of genes (around 32,000) which contrasted with the much higher figure around 150,000 which was previously envisioned. Attempts to make a global assessment of the use of alternative splicing are recent and rely essentially on the comparison of genomic mRNA and EST sequences as reviewed by Thanaraj and Stamm in the first chapter of this volume. Most recent estimates suggest that 40-60% of human genes might be alternatively spliced, as opposed to about 22% for C. elegans.

During the last few years, tremendous progress has been made in understanding various aspects of pre-mRNA processing. This book, with contributions from leading scientists in this area, summarizes recent advances in nuclear pre-mRNA processing in plants. It provides researchers in the field, as well as those in related areas, with an up-to-date and comprehensive, yet concise, overview of the current status and future potential of this research in understanding plant biology.

2.4 Regulation of Transcription by Termination2.4.1 Transcription Attenuation, Promoter Upstream/Associated Transcription, and Pausing of RNApII; 2.4.2 Alternative Polyadenylation and Termination; 2.5 Mechanisms of Termination by Other RNA Polymerases; 2.6 Future Perspectives; Acknowledgments; References; 3: Posttranscriptional Gene Regulation by an Editor: ADAR and its Role in RNA Editing; 3.1 Introduction; 3.2 The RNA Editing Kinship; 3.3 The ADAR Gene Family; 3.4 The Role of RNA in the A-to-I Editing Mechanism; 3.5 Splice Site Alterations.