Gene regulation in eukaryotes

One known example of inactivation of a gene by condensation of euchro-matin to heterochromatin is the inactivation of one X chromosome in mammalian females. This occurs early in embryonic development, at the 20-cell stage. It has been suggested that this is achieved by heavy methylation. 

Hemoglobin (Chapter 14) is an example of a developmentally controlled complex gene family in which the presence of a- and /3-like subunits depends on the 

Gene rearrangement is a very complex process, and a detailed consideration is beyond the scope of this book. We discuss only the turning on of immunoglobulin gene expression in which DNA rearrangement positions a promoter in the vicinity of a B cell-specific enhancer (Chapter 14). 

If a large amount of protein is required over an extended period of time, this could be achieved by increasing the stability of mRNA. Gene amplification would be unnecessary. 

Little is known about what determines mRNA half-life. We do not know whether the stability of certain mRNAs, such as hemoglobin mRNA in reticulo- 

Regulationof gene expression in eukaryotes proceeds primarily by control of transcription as in prokaryotes. Some systems are also regulated at the translational level. 

However, synthesis of mRNA in eukaryotes is not a simple matter of initiation at a promoter, as it is in prokaryotes, but includes several steps in which the primary transcript is converted to mRNA (Chapter 25). Control of these processing steps is also used to regulate gene expression in eukaryotes. 

Diseases Associated with Elevated Levels of RNase Activity in Body Fluids or Cell Extracts 

Neurological infectious diseases poly-C degrading RNase 

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The effects of chromosome structure on gene regulation in eukaryotes have no clear parallel in prokaryotes. In the eukaryotic cell cycle, interphase chromosomes appear, at first viewing, to be dispersed and amorphous (see Figs 12-41, 24-25). Nevertheless, several forms of chromatin can be found along these chromosomes. About 10% of the chromatin in a typical eukaryotic cell is in a more condensed form than the rest of the chromatin. This form, heterochromatin, is transcriptionally inactive. Heterochromatin is generally associated... 

Struhl, K. (1999) Fundamentally different logic of gene regulation in eukaryotes and prokaryotes. Cell 98, 1-4. 

All of the following statements about gene regulation in eukaryotes is true, except... 

Despite these differences, some aspects of gene regulation in eukaryotes are quite similar to those in prokaryotes. In particular, activator and repressor proteins that recognize specific DNA sequences are central to many... 

Matys, V., Kel-Margoulis, O.V., Fricke, E., et al. (2006) TRANSFAC and its module TRANSCompel transcriptional gene regulation in eukaryotes. Nucleic Acids Res. 34, D108-D110. 

Outline the roles of coactivators and corepressors in transcription complexes. Contrast mechanisms of positive and negative gene regulation in eukaryotes. 

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