ABSTRACT
Two numbers underscore the central importance of gene regulation in making the reader who the people are. In this chapter the authors necessarily describe individual components of the network separately-chromatin accessibility, histone modifications, DNA-binding proteins, DNA methylation, promoters, and enhancers-but it is important to bear in mind that no one of them is independent of the others. In this chapter, the authors are concerned with RNA polymerase II, which transcribes all protein-coding genes and most noncoding RNA genes. It is best known for its role in holding sister chromatids together but it is also involved in stabilizing promoter-enhancer interactions. Enhancers are responsible for most of the tissue- and cell-specificity of gene expression. Functional alternative splicing can have a variety of results. Alternatively spliced exons may encode signals governing different intracellular localizations. In contravention of the central dogma, there are examples in which the DNA sequence of a gene does not fully determine the sequence of its transcript.
