What is the histone code? Different chemical marks, such as acetylation, methylation, or phosphorylation, are made to numerous residues on the N-terminal tails of histone proteins. Some posit that they act as readable and specific landing pads for proteins that control chromatin modeling and transcriptional regulation. The marks appear to be clustered in different regulatory groups signifying "on" and "off" portions of the genome, and some of the proteins that make and read these marks seem to have properties that allow the patterns to spread and be passed on to new histones.
Since when was this idea new? Reigning theory in the past suggested that histone modifications created charge and folding differences to make nucleosomes grip the DNA more tightly or loosely. Though such mechanisms are still suspected, it's obvious that more is involved. A decade ago, researchers started postulating that histone acetylation was doing more than adding and subtracting ...
