Involved in pre-mRNA splicing as component of the U5 snRNP complex that is involved in spliceosome assembly. Component of the U5 snRNP complex composed of the U5 snRNA and at least PRPF6, PRPF8, SNRNP200, EFTUD2, SNRNP40, DDX23, TXNL4A and CD2BP2. Interacts directly with TXNL4A and PRPF6. Interacts (via GYF domain) with CD2 (via Pro-rich sequence in the cytoplasmic domain). Interacts with PQBP1. Predominantly nuclear.