Bromodomains shake the hegemony of pan-acetyl antibodies.

Acetylation signaling pathways are involved in numerous cellular processes and are used as therapeutic targets in several disease contexts. However, acetylated proteins only represent a minor fraction of the full proteome, and the identification and quantification of acetylated sites remain a technological challenge. Currently, pan-acetyl antibodies are used to increase the abundance of acetylated peptides through affinity purification before MS analysis. These antibodies are powerful reagents, but they are hampered by a lack of specificity, affinity, and batch-to-batch reproducibility. In this issue, Bryson et al. (Proteomics 2015 15, 1470-1475) present an interesting alternative to these antibodies, in the form of bromodomains. These domains specifically recognize acetylated lysines, and were successfully used in this study to enrich for acetylated peptides before MS analysis. Future development of this pioneering approach could help overcome this limiting step in the characterization of acetylproteomes.