Function : Involved in mRNA processing and export (PubMed:1429834 PubMed:8675010 PubMed:15542855 PubMed:19061647). Required for efficient splicing of a large set of pre-mRNAs by efficient co-transcriptional recruitment of the splicing machinery (PubMed:19061647 PubMed:23209445). Remains associated with the mRNP during early steps of translation elongation (PubMed:15542855).