SF3A1 (splicing factor 3a subunit 1) is a critical component of the 17S U2 small nuclear ribonucleoprotein (snRNP) complex within the spliceosome, the ribonucleoprotein machinery responsible for removing introns from pre-mRNA 123. As part of the SF3A subcomplex, SF3A1 directly participates in early spliceosome assembly and mediates branch-site recognition by promoting selection of the pre-mRNA branch-point adenosine, the catalytic nucleophile for the initial splicing transesterification reaction 12. SF3A1 functions in sequential spliceosomal complex assembly, including the E, A, and B complexes 45. Structurally, SF3A1 contains two tandem SURP domains; SURP1 binds transiently to splicing factor SF1 with a dissociation constant of ~20 μM, facilitating U2 snRNP recruitment to early spliceosomal complexes 6. SF3A1 is also recognized as a bridging factor in spliceosome assembly, interacting with U1 snRNP stem-loop 4 through the SF3A1 protein 7. Dysregulation of SF3A1 has clinical implications: SF3A1 polymorphisms show associations with pancreatic cancer risk 8, and aberrant SF3A1 expression drives prostate cancer progression through enhancer-mediated regulation 9. Additionally, SF3A1 represents a therapeutic target in myocardial ischemia/reperfusion injury via mitochondrial energy metabolism regulation 10.