A capped 5′UTRPab1 or an uncapped 5′UTRPab1 with a stable upstream hairpin was used for measuring the cap-dependent or cap-independent initiation activity, respectively. These RNA constructs were incubated with the yeast extracts from either WT or ΔSbp1 cells with an increasing amount of Sbp1 protein added. As shown in Figure 6A and C (the second column), a decreased translation activity in the presence of an increasing amount of Sbp1 indicated an inhibitory function of this protein in both cap-dependent and cap-independent initiation of the Pab1 mRNA. In contrast, translation of the 5′UTR4E as well as 5′UTRCrPV was almost unchanged as the concentration of Sbp1 increases (Fig. 6D,E).