FIG. 4.

Upstream determinants for Mus81-Mms4 cleavage. Various 3′ flap (left) or gapped duplex (right) substrates were designed with the indicated flap (Y) or upstream (X) sizes given in nucleotides. Substrates were incubated with (+) or without (−) Mus81-Mms4, and the products were resolved on a 10% sequencing gel. Substrates were assembled as follows: 3′ flap with a 24-nt branch (*888/1128/994) or 20- to 0-nt branches (*1078-1084/1128/994); gapped-duplex substrates (*1115-1119/1128/994). A minus sign indicates a lane in which the untreated substrate remained in the well. The values on the left and right are numbers of nucleotides. Enz, enzyme; oligo, oligonucleotide; T, template.