Figure 3.

Reconstitution of CF I cleavage activity requires the addition of all five peptides. Whole-cell extract from wild-type yeast strain FY86 before fractionation on a Hi-Trap Q column cleaves the precursor and polyadenylates the upstream cleavage product. CF I and CF II are sufficient in the absence of PAP and PF I to reconstitute cleavage activity when mixed. The addition of all five peptides of CF I reconstitutes cleavage activity when mixed with CF II (lane 20). The downstream cleavage product is rapidly degraded and is not detectable under these conditions.