Harpers

RNA SYNTHESIS, PROCESSING, & MODIFICATION / 357GTFs and RNA polymerase with promoters—or inone step by the recognition of the promoter by a preformedGTF-RNA polymerase holoenzyme complex.• Transcription exhibits three phases: initiation, elongation,and termination. All are dependent upon distinctDNA cis-elements and can be modulated bydistinct trans-acting protein factors.• Most eukaryotic RNAs are synthesized as precursorsthat contain excess sequences which are removedprior to the generation of mature, functional RNA.• Eukaryotic mRNA synthesis results in a pre-mRNAprecursor that contains extensive amounts of excessRNA (introns) that must be precisely removed byRNA splicing to generate functional, translatablemRNA composed of exonic coding and noncodingsequences.• All steps—from changes in DNA template, sequence,and accessibility in chromatin to RNA stability—aresubject to modulation and hence are potential controlsites for eukaryotic gene regulation.REFERENCESBusby S, Ebright RH: Promoter structure, promoter recognition,and transcription activation in prokaryotes. Cell 1994;79:743.Cramer P, Bushnell DA, Kornberg R: Structural basis of transcription:RNA polymerase II at 2.8 angstrom resolution. Science2001;292:1863.Fedor MJ: Ribozymes. Curr Biol 1998;8:R441.Gott JM, Emeson RB: Functions and mechanisms of RNA editing.Ann Rev Genet 2000;34:499.Hirose Y, Manley JL: RNA polymerase II and the integration ofnuclear events. Genes Dev 2000;14:1415.Keaveney M, Struhl K: Activator-mediated recruitment of theRNA polymerase machinery is the predominant mechanismfor transcriptional activation in yeast. Mol Cell 1998;1:917.Lemon B, Tjian R: Orchestrated response: a symphony of transcriptionfactors for gene control. Genes Dev 2000;14:2551.Maniatis T, Reed R: An extensive network of coupling among geneexpression machines. Nature 2002;416:499.Orphanides G, Reinberg D: A unified theory of gene expression.Cell 2002;108:439.Shatkin AJ, Manley JL: The ends of the affair: capping and polyadenylation.Nat Struct Biol 2000;7:838.Stevens SW et al: Composition and functional characterization ofthe yeast spliceosomal penta-snRNP. Mol Cell 2002;9:31.Tucker M, Parker R: Mechanisms and control of mRNA decappingin Saccharomyces cerevisiae. Ann Rev Biochem 2000;69:571.Woychik NA, Hampsey M: The RNA polymerase II machinery:structure illuminates function. Cell 2002;108:453.