Fig. 5

The heme level and heme-dependent enzyme activities are decreased in SFXN2-KO cells. a The relative labile heme level was lower in SFXN2-KO cells than in control cells. b Total heme (hemin) was isolated from control and SFXN2-KO cells. Representative mass spectra are shown. c The total hemin content was significantly lower in SFXN2-KO cells than in control cells. n = 3. **p < 0.01. d, e Activities of complexes II–III and IV were significantly lower in SFXN2-KO cells than in control cells. n = 3 each. **p < 0.01. f Complex I activity did not differ between SFXN2-KO and control cells. n = 3 each. g The relative OCR was measured in control and SFXN2-KO cells. The maximum OCR was significantly decreased in SFXN2-KO cells after application of 10 μM FCCP. n = 4 each. ****p < 0.0001. h Representative mass spectra of the ms²i⁶A (2-methylthio-N⁶-isopentenyladenosine) modification in control and SFXN2-KO cells. Unmodified adenosine (A) was examined as a loading control. The ms²i⁶A level did not differ between control and SFXN2-KO cells