FIGURE 5.
MS/MS spectrum of CB-released TM8. TM8 is released by CB during or following trypsin digestion. The peptide sequence is K300↓AGVQQPVYATIGSGIVNTAFTVVSLFVVER330↓A corresponding to L7–8 and TM8 at the membrane/cytoplasm interface (Fig. 1A). This peptide elutes from the HPLC column at 42.73 min (43% organic solvent). The indicated y-(read C to N terminus, blue) and b (read N to C terminus, red)-ion series confirm the identity of this peptide with the following Sequest scoring parameters: XCorr, 5.53, peptide probability, 7.43 × 10-8; ΔCn, 0.75; and preliminary score, 1471.6.