SNRPA1, also known as U2 small nuclear ribonucleoprotein A, is a component of the U2 snRNP that forms a complex with U2 snRNP B (U2B). Together, U2 snRNP A and U2 snRNP B form a complex that binds to the U2 snRNA hairpin IV. The configuration of this U2 snRNP A/U2 snRNP B dimer and the subtle variations of a few key residues regulate the snRNP-RNA-binding specificity. U2 snRNP A is a 255 amino acid protein, and two isoforms exist as a result of alternative splicing events. Recombinant human SNRPA1 protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography.