Protein modification part1 of 3

Introduction - protein post-translational modifications

by:Andrew J. Bannister and Colyn Crane-Robinso

Organisms exist in a continually changing environment: they are constantly bombarded and challenged with stimuli to which they must respond in order to survive. Such responses require three essential steps: detection/initiation, transmission and read-out. In practice, a cell detects a particular signal, such as the presence of a hormone or the appearance of a potentially damaging free radical, and activates a series of enzymes in a signalling cascade that ultimately determines the appropriate biological outcome. These responses are largely achieved via PTMs (post-translational modifications) of pre-existing proteins by specific enzymes. In this series of articles, experts in the relevant subject areas review our current understanding of the major PTMs and how they affect their target proteins.

Histone acetylation -
by: playing tag Colyn Crane-Robinson
Acetylation of the e-amino group of specific lysine residues of core histones – principally but not exclusively in their unstructured N-terminal tails – is a key biochemical modification for establishing the transcriptional competence of genes bound by such histones. High resolution mapping of acetylated core histones by chromatin IPs (ChIPs) has shown them to be preferentially located at the promoters and enhancers of active genes rather than throughout the transcribed regions. Particular distributions of acetylated lysines are part of the nucleosomal ‘histone code’ that defines and to a considerable extent determines the functional status of the local chromatin. HHe istone acetylation is deposited and removed by numerous histone acetyltransferases (HATs) and deacetylases (HDACs) and acetyl-lysines are recognized (i.e. the histone code is ‘read’) by bromodomain-containing proteins.