| Function |
Required for pre-spliceosome formation, which is the first step of pre-mRNA splicing. This protein is associated with snRNP U1. Two commitment complexes, CC1 and CC2, have been defined in yeast. CC1 is a basal complex dependent only on the 5' splice site. CC2 is a complex of lower mobility and is dependent on a branchpoint as well as a 5' splice site region. This protein is involved in CC2 formation where it binds to the branchpoint binding protein MSL5, bridging the U1 snRNP-associated 5' splice site and the MSL5-associated branch point 3' intron splice site. {ECO:0000269|PubMed:10978320, ECO:0000269|PubMed:15020406, ECO:0000269|PubMed:9150140}.
|