Fig. 1.

Identification of a sequencing error for the deposited Cox2 subunit II (CoxB2). (A) MS spectrum of the trypsin digested Cox2 subunit II (band in Fig. S1C). Masses and sequence regions of assigned signals are labeled. Asterisks mark peaks verifying the new sequence regions. The bar plot aligns identified peptide mass fingerprint (PMF) fragments to the corresponding protein sequence regions. The arrow indicates the start of the incorrectly annotated Cox2 subunit II sequence; (B–D) MS/MS spectra of 1,014.6, 1,947.9, and 2,246.1. The manually interpreted peptide sequence is indicated (N-terminal b-ions, C-terminal y-ions, immonium ions). A differentiation between leucine/isoleucine (L/I) and lysine/glutamine (K/Q) is not possible. Because of the C-terminal specificity of the trypsin digest at lysine/arginine (K/R), the C terminus is solely indicated as K in C and D.