Figure 6.

Photolabeling a third residue, Tyr⁶², in the cholesterol binding pocket in E73Q mVDAC1. A, an MS1 doublet corresponding to the peptide TSSGSANTETTKVNGSLETKYRWTEY from E73Q mVDAC1 photolabeled with KK174 (z = 5) and coupled to light and heavy FLI-tag. B, fragmentation (ETD) spectra corresponding to the feature in A. Site defining ions localize KK174 photolabeling to Tyr⁶². C, the same cholesterol binding pose as in Fig. 2E showing Tyr⁶², Glu⁷³, and Thr⁸³. D, space filling view of the binding pocket mapped by KK174 and LKM38.