Molecular Machines That Control
Genes Robert Tijan
Scientific American
February 1995, Vol. 272, No. 2, pp. 38-45
The proteins regulating DNA
transcription are discussed in this article. Transcription is the process in which a gene that specifies a
protein (more precisely, the linear sequence of
amino acids from which a protein forms, as explained below) is copied and imprinted upon messenger RNA. This messenger RNA then subsequently serves as the template for the assembly of linear strings of amino acids that then subsequently fold, spontaneously, into
the three dimensional configurations conferring specific functional properties to specific proteins. (Note: Several different strings of amino acids specified by specific genes may nonetheless fold into the same functional protein.)
The proteins involved in regulating transcription divide into four kinds: activators, repressors, coactivators, and basal factors.
activators enhance transcription. They bind to genes at sites called enhancers and help to determine which genes are switched on.
repressors counter the activity of activators. They bind to a select set of genes termed. silencers. Coactivators integrate signals from activators and possibly repressors and then
subsequently transmit the integrated signal to the basal factors. Basal factors position RNA polymerase (another protein) at the beginning of the protein-coding section of a gene.
A suggestion of how important these transcription factors are may be appreciated in their possible involvement, through faulty operation, in diseases as diverse as asthma, cancer, heart disease, immune disorders, and viral infections: All these disorders result, to a great extent, from excess or deficient production of one or more proteins.
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