Figure 4: MALDI ToF MS peptide mapping analysis and amino acid sequence of Fibrillarin. [A] Mass spectrum range m/z 2500–3000 shows Fibrillarin epitope peptide in early eluting fraction (fraction 3) upon binding to anti-His antibody. [B] Mass spectrum of early eluting fraction (fraction 4) in the absence of anti-His antibody remains empty. [C] Mass spectrum of tryptic Fibrillarin peptides. [D] Amino acid sequence in single letter code of recombinant Fibrillarin showing sequence coverage after trypsin digest in bold letters. The shaded sequence displays the epitope motif that is recognized by the ant-His antibody. Matrix: DHB, n.i: not identified, E: derived from trypsin autoproteolysis, •: sodium adduct.