RNA-binding protein that regulates alternative splicing events by binding to 5'-UGCAUGU-3' elements. Prevents binding of U2AF2 to the 3'-splice site. Regulates alternative splicing of tissue-specific exons and of differentially spliced exons during erythropoiesis. Seems to act as a coregulatory factor of ER-alpha (By similarity). Interacts with ER-alpha N-terminal activation domain. Extended N-terminus.