Fig. 9
From: Human MFAP1 is a cryptic ortholog of the Saccharomyces cerevisiae Spp381 splicing factor
Recruitment of Prp38, Snu23 and MFAP1/Spp381 to the human or yeast spliceosomes. Human Prp38, Snu23, MFAP1 and other B-specific proteins enter the spliceosome at the complex B stage independent of the tri-snRNP. In contrast, yeast Prp38, Snu23 and the hsMFAP1 ortholog scSpp381 are tri-snRNP-specific proteins and thus first bind to the tri-snRNP. Subsequently, the tri-snRNP enters the spliceosome to form complex B. In human and yeast, Prp38, Snu23 and MFAP1/Spp381 leave the spliceosome during B to Bact complex transition