... for the insertion of ISP into an immature bc1complex and that the association of the Qcr9p subunit with the bc1complex precedes the binding of ISP. Infact, the direct absence of ISP (DISP), ... bc1complex is alsounknown. Furthermore, as in the case of the biogene-sis of other multi-subunit complexes of the mitochon-drial respiratory chain, the assistance of specificchaperone proteins is ... kDa bc1sub-complex. Therefore, the pres-ence of both Qcr9p and Bcs1p is required for the inser-tion of ISP into the bc1sub-complex, but the presence of only one of these two subunits does...