FIGURE 4.

Cytoplasmic PUS10 has Ψ synthase activity. (A) Ψ55 synthase activities of h-PUS10, nh-PUS10, and ch-PUS10 were determined by 2D-TLC analyses as in Figure 1, after using these proteins to treat [α-³²P]CTP-labeled tRNA^Trp and tRNA^Ala. (B) Ψ54 synthase activities of ch-PUS10 and i-PUS10 were determined by 2D-TLC analyses as in Figure 1, after using these proteins to treat [α-³²P]UTP-labeled tRNA^Trp and tRNA^Ala. The tRNAs were pretreated with TrmI to produce m¹A58, which enhances Ψ54 synthesis by PUS10.