
Proteins are constructed from a string of amino acids, and the amino acid sequence is coded in a gene. But how does the cell know which of its many genes to use in synthesizing proteins? Gene regulation is accomplished via a number of complex mechanisms. For instance, methyl groups are used to tag both the DNA as well as the histone proteins about which the DNA is wrapped. You can read more about histones
here and
here. In addition to such methylation, histones can also vary by tiny differences in their amino acid sequence. Such histone variants serve as yet another type of tag used for gene regulation. Now
new research is revealing the profound complexity of this mechanism.
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