Splicing factor 3A subunit 3

SF3A3 (splicing factor 3A subunit 3) is a 501-amino acid component of the 17S U2 small nuclear ribonucleoprotein complex within the spliceosome (UniProt: Q12874). It participates in early spliceosome assembly and branch-site recognition during intron removal from pre-mRNA, serving as part of the SF3A subcomplex that enables formation of pre-catalytic spliceosome complexes required for pre-mRNA splicing.

SF3A3 is expressed broadly and functions in a core cellular process fundamental to gene expression. No baseline disease associations are documented in UniProt for this gene.

In Alzheimer's Disease, SF3A3 is upregulated in post-mortem brain tissue relative to age-matched controls, with a mean log2 fold-change of +0.73 across subcellular fractions (Chaparral AD proteomics). This modest but consistent increase suggests potential involvement of splicing machinery in AD pathology, though the functional consequence of elevated SF3A3 in AD brain remains to be determined.