The effect of cyt f mutants on the formation of cyt f-PC complexes at 10 mM ionic strength. (A) The number of complexes formed as a function of Cu-Fe distance for wild-type and cyt f mutants. Other conditions were as for Fig. 4. (B) Position of the mutants on cyt f. Inhibition of complex formation: Class I, ≤30% (R88, K94, K110, K164, and K165), light gray; Class II, 30–60% (K58, K66, K121, K122, R156, and R207) dark gray with labels in italics; Class III, > 60% (K65, K188, and K189), black with labels underlined.