Tandem MS analysis of HeT-A Gag protein by mass spectrophometry.

(A) MS/MS of ion m/z shows an extensive y-ion series and the presence of phosphorylation at serines 216 or 221, as indicated by the arrow. (B) Line diagram of different forms of HeT-A Gags (M1, M2, and M3) that were generated by site directed mutagenesis. Primer sets and template used for site directed mutagenesis are described in Table 2.