Online Encyclopedia
Gene regulation
Gene regulation is the general term for cellular control of protein synthesis at the DNA-RNA transcription step. Since this is the root of the central dogma of biology, gene regulation gives the cell the broadest control over structure and function. The level of broad control, however, comes at the expense of timing; since the effects of any change in gene regulation are far downstream, gene regulation is often used for processes which have relatively long-term effects, in contrast to signal transduction which is how the cell handles events quickly (though often it results in gene regulation). Examples of gene regulation include heat shock proteins generated by Drosophila.
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Mechanisms for gene regulation
Chemical modification of DNA
DNA is known to be able to be methylated.
Structural modification of DNA
DNA's ability to be transcribed can be dictated by its structure. DNA which is not highly supercoiled lies more exposed and therefore can be more easily transcribed. Protein complexes called histones are responsible for the amount of supercoiling of DNA, and these complexes can be temporarily modified by processes such as phosphorylation or permanently modified by processes such as methylation. Such modifications are considered to be responsible for permanent changes in cell expression levels, such as those involved in development.
Regulation of transcription machinery
Genes can be regulated is by transcription factors. Transcription factors generally simultaneously bind DNA as well as the RNA synthase which begins the transription of DNA into RNA. By altering structure after a change such as a phosphorylation or proteolysis, the activity of a transcription factor can be enhanced, repressed, or even abolished.
Controlling the concentration of transcription factors, often by gene expression itself, can also alter the activity of a transcription factor, and bring about an ancillary change in gene expression.