Involved in pre-mRNA splicing as a component of the splicing factor SF3A complex that contributes to the assembly of the 17S U2 snRNP, and the subsequent assembly of the pre-spliceosome 'E' complex and the pre-catalytic spliceosome 'A' complex. Involved in pre-mRNA splicing as a component of pre-catalytic spliceosome 'B' complexes, including the Bact complex. Interacts directly with the duplex formed by U2 snRNA and the intron. Component of splicing factor SF3A which is composed of three subunits; SF3A3/SAP61, SF3A2/SAP62 and SF3A1/SAP114. SF3A1 functions as scaffold that interacts directly with both SF3A2 and SF3A3. SF3A associates with the splicing factor SF3B and a 12S RNA unit to form the mature 17S U2 small nuclear ribonucleoprotein complex (17S U2 snRNP). Identified in the spliceosome 'E' complex, a precursor of the spliceosome 'A' complex. Identified in the spliceosome 'A' and 'B' complexes. Identified in the spliceosome 'C' complex. Interacts with HTATSF1. Belongs to the SF3A2 family.