FIGURE 3.

La (Sla1) and Trm1 cooperate to promote tRNA folding, accumulation, and functionality in fission yeast. Sla1 is represented by the amino-terminal domain of the human La protein (structure 2VOO from Kotik-Kogan et al. 2008). A combination of La-mediated tRNA chaperone activity and Trm1 modification ensures proper tRNA folding such that pre-tRNAs accumulate and undergo aminoacylation (top), while misfolded pre-tRNAs are often degraded by the nuclear surveillance machinery in the absence of La and Trm1 (bottom). Some misfolded or unmodified pre-tRNAs may escape nuclear surveillance and are exported to the cytoplasm, where they may get aminoacylated and function in translation (bottom).