Figure 4

Only Prp40 FF domains 1–2 are essential in vivo. A, A strain with Protein A fused to the full-length Prp40 (FF1-4ProA) shows no signficant difference in growth to the wild-type. FF domain deletions from the C-terminus by insertion of Protein A into the respective FF domain locus resulted in a viable mutant that lacks FF domains 3–4. However, replacements of FF domains 4 or 3–4 could not be found and thus may be lethal. B, The mutant lacking FF domains 3–4 is viable but shows a growth defect compared to the wild-type controls. C, Summary of domains and functional motifs in Prp40. Numbers are amino acid sequence positions. Regions 1 and 2 are similar to RNA-binding domains. These and three other motifs, NES 1 and 2 (nuclear export signals) and an arginine-rich motif (ARM) have been deleted [Δ] or mutated by Murphy et al. [31]. The phenotypes of these mutations are shown below (ts = temperature-sensitive). Note that the predicted coiled-coil region indicated as bar between FF2 and FF3 in A is not shown here as it has no known function.