Fig. 7.

Native c-RAF active-site peptide detected in H82 proteomes. (A) MS1-extracted ion chromatograms of the probe-labeled active-site peptide for c-RAF identified in H82 proteomes. Pretreatment of heavy H82 proteomes with ritanserin (100 µM) results in blockade of c-RAF active-site probe labeling (SR > 6). Pretreatment with ketanserin (100 µM) results in no inhibition (SR = 1). (B) MS2 spectra of probe-modified peptide corresponding to the active site of c-RAF. Major b- and y-ion fragments derived from neutral losses of the precursor (M) are shown in red in the spectrum. All experiments were measured two to three times (technical replicates in LC-MS) using data from two independent biologic replicates performed on separate days (n = 6). (A) and (B) are representative images from a single measurement. m/z, mass-to-charge ratio.