Precise Characterization of Human Histones in the H2A Gene Family by Top Down Mass Spectrometry

Abstract
Top Down analysis revealed that at least fourteen genes encoding histone H2A are coexpressed in HeLa cells. Characterization of these species1 revealed that all except H2A.Z and H2A.F/Z were α-N-acetylated, H2A.O and H2A.C,D,I,N,P were the most abundant, and those exceeding ∼10% abundance lacked post-translational modifications. This unequivocal identification of H2A forms illustrates the advantages of Top Down Mass Spectrometry and provides a global perspective of H2A regulation through the cell cycle. Keywords: histone H2A • Fourier transform mass spectrometry (FTMS) • Top Down • post-translational modification (PTM) • SILAC • cell cycle • ubiquitination • electron capture dissociation (ECD) • histone code • chromatin