Evolutionary Change
A major question in evolutionary biology is how important tinkering with promoter sequences is to evolutionary change, for example, the changes that have occurred in the human lineage after separating from chimps.
Some evolutionary biologists, for example Allan Wilson, have proposed that evolution in promoter or regulatory regions may be more important than changes in coding sequences over such time frames.
A key reason for the importance of promoters is the potential to incorporate endocrine and environmental signals into changes in gene expression: A great variety of changes in the extracellular or intracellular environment may have impact on gene expression, depending on the exact configuration of a given promoter: the combination and arrangement of specific DNA sequences that constitute the promoter defines the exact groups of proteins that can be bound to the promoter, at a given timepoint. Once the cell receives a physiological, pathological, or pharmacological stimulus, a number of cellular proteins are modified biochemically by signal cascades. By changes in structure, specific proteins acquire the capability to enter the nucleus of the cell and bind to promoter DNA, or to other proteins that themselves are already bound to a given promoter. The multi-protein complexes that are formed have the potential to change levels of gene expression. As a result the gene product may increase or decrease inside the cell.
Read more about this topic: Promoter (genetics)
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