PHF5A is a subunit of the splicing factor 3b protein complex. Splicing factor 3b, together with splicing factor 3a and a 12S RNA unit, forms the U2 small nuclear ribonucleoproteins complex (U2 snRNP). The splicing factor 3b/3a complex binds pre-mRNA upstream of the intron's branch site in a sequence-independent manner and may anchor the U2 snRNP to the pre-mRNA. PHF5A contains a PHD-finger-like domain that is flanked by highly basic N- and C-termini. This protein belongs to the PHD-finger superfamily and may act as a chromatin-associated protein. Recombinant human PHF5A protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.