SDS-PAGE of labeled F1-γ108-atto488 and His6ε99-atto647N (12% PA gel according to Schaegger and von Jagow[58], with Coomassie blue staining of F1-ATPase subunits in lanes 2 to 4, and fluorescence images in lanes 5 and 6. Lane 1 is the molecular weight standard. Lane 2 shows F1-γ108-atto488. Atto488-maleimide labeling resulted in an additional labeling of cysteines of residual δ subunit (lane 5). Lane 3, ε99-atto647N preparation showing two fluorescence-labeled products ε* and ε** (lane 6, for details see text). Lanes 7 and 8: SDS-PAGE of labeled FoF1-a-C-Term-cys. Lane 7 shows Coomassie blue-stained subunits of FoF1-ATP synthase, lane 8 specific Alexa488-maleimide labeling of the cys residue introduced to the C-terminus of subunit a (for details see text).