Читать книгу Neurobiology For Dummies - Frank Amthor - Страница 58

Cells can modify the rate at which specific gene products (protein or RNA) are produced. This occurs as cells proceed down their developmental pathways, but it also occurs in response to environmental stimuli. Gene expression can be modified at all the stages of transcription, RNA processing, and post-translational protein modification.

One of the main mechanisms of regulating DNA expression is methylation by methyltransferase enzymes (adding methyl groups to adenine or cytosine nucleotides in the DNA), which occurs on cytosine nucleotides. Another important regulation mechanism is histone acetylation, when histone acetyltransferase enzymes (HATs) dissociate the histone complex from a section of DNA. The presence of histones blocks expression, so by removing histones, transcription can proceed. Methylation and histone deacetylation may act simultaneously to control DNA expression.