LYRM7/MZM1L is a UQCRFS1 chaperone involved in the last steps of mitochondrial Complex III assembly in human cells

► Human LYRM7 is identified as the yeast Mzm1 functional homolog ► LYRM7/MZM1L is a new human Complex III assembly factor ► MZM1L is a UQCRFS1 chaperone, binding and stabilizing it prior to its translocation ► Correct insertion of UQCRFS1 to mature Complex III depends on MZM1L stoichiometry