FIGURE 1.

Model for involvement of Coa2, Cox10, and Cox15 in Cox1 maturation. Newly synthesized Cox1 is initially trapped in the Mss51/Cox14/Coa3/Ssc1 intermediate. Coa1, presumably in concert with Coa2, triggers further progression of Cox1 to the state where it is competent to receive heme a moieties. Such progression is coupled to Cox10 oligomerization. Population of the heme a and a₃ sites culminates with the involvement of Shy1 and addition of Cox5a and Cox6 subunits. The C-terminal segment of Cox1 used to trigger Cox10 oligomerization is shown as C-term.