Identified crosslink between murine ACAD9 and ND2 (spectrum in Fig EV1). ND2: Red - crosslinked peptide, green - C-terminal helix, Yellow - crosslinked Lys319. ACAD9: Orange - crosslinked Lys504. Sequences of identified crosslinked peptides from mouse and the homologous sequences from the human proteins are presented (yellow: crosslinked lysine). 