Plays a critical role in both constitutive and enhancer-dependent splicing by mediating protein-protein interactions and protein-RNA interactions required for accurate 3'-splice site selection. Recruits U2 snRNP to the branch point. Directly mediates interactions between U2AF2 and proteins bound to the enhancers and thus may function as a bridge between U2AF2 and the enhancer complex to recruit it to the adjacent intron. U2AF1 Protein, Human, Recombinant (GST) is expressed in E. coli expression system with N-GST tag. The predicted molecular weight is 54.9 kDa and the accession number is Q01081.