Human ARID4A and ARID4B are homologous proteins that are important in controlling gene expression and epigenetic regulation but have distinct functions. Previous studies have shown that the N-terminal domain of ARID4A is an unusual interdigitated double Tudor domain with DNA-binding activity. However, how the Tudor domain of ARID4B differs from that of ARID4A remains unknown. Here, we found that the ARID4B Tudor domain has significantly weaker DNA affinity than the ARID4A Tudor domain despite sharing more than 80% sequence identity.
