Fig 5.

Genetic interaction between UPF2 and upf1 alleles impaired in different Upf1 activities. Plasmids (pYX142) carrying the indicated UPF1 alleles were individually transformed into the upf1Δ UPF2 strain (HFY871) or the upf1Δ upf2Δ strain (HFY466). The resulting strains were analyzed for NMD activity and the ability to prevent nonsense suppression. The amount of canavanine in the medium (0, 75, and 200 μg/ml) is shown. (A) Function of different upf1 alleles in promoting NMD in the presence or absence of UPF2. Total RNA was isolated from strains harboring different upf1 alleles. The steady-state levels of the CYH2 pre-mRNA and the can1-100 and ALR1 mRNAs were analyzed by Northern blotting, using random-primed probes specific for CYH2, CAN1, ALR1, or SCR1 transcripts with the latter serving as a loading control. (B) Function of different upf1 alleles in preventing can1-100 suppression in the presence or absence of UPF2. Strains harboring different upf1 alleles were assayed for their ability to prevent can1-100 suppression as described in the legend to Fig. 2C.