Identification of the photoaffinity-labeled proteins in complex I. (A), 2-D gel analyses (BN- and 10% tricine-SDS PAGE) in the presence (a) and absence (b and c) of 6M urea. In (c), SMP was incubated with rotenone (10 μM) before irradiation. The arrows indicate the major radioactivity peaks, 85 kDa, 50kDa, and 33kDa. (B) and (C), a typical gel pattern of 3-D gel analyses (BN-, 10% tricine- with or without 6M urea-, and 16% tricine SDS-PAGE). The gel was stained with silver. The spots 1, 2, 3, and 4 were identified as subunits ND5, ND4, ND2, and ND1 respectively.