Figure 5.

Representative isoforms with PTMs beyond the N-terminal tail and with phosphorylation. (a) Intact H3 isoforms observed from second dimension WCX-HILIC analysis of H31 fraction as shown in Figure 1 (a). (b) Example tandem mass spectra for an isoform displaying modification beyond the histone tail (top) and a phosphorylated isoform (bottom). Insets show the corresponding parent ion spectra with precursor ions selected for fragmentation boxed. PTM, post-translation modification; WCX-HILIC, weak cation exchange-hydrophilic interaction liquid chromatography.