Figure 1.

Cytosolic tRNA^His processing in eukaryotes. After removal of 5′-leader and 3′-trailer sequences by the nucleus-localized RNase P and RNase Z (orange), CCA- (cyan) and G-1-addition (green) take place in the cytosol. However, it is not clear whether these events occur at random or follow a sequential order, due to different substrate preferences of the involved enzymes. Furthermore, these events can be affected by the nature of the discriminator base 73 that is located across the -1 position (as an example, A73 is indicated in red).