Predicted to enable transcription coactivator activity and transcription corepressor activity. Involved in regulation of gene expression. Acts upstream of with a positive effect on BMP signaling pathway. Acts upstream of or within several processes, including Kupffer's vesicle development; anterior/posterior pattern specification involved in pronephros development; and circulatory system development. Predicted to be located in bicellular tight junction. Predicted to be active in cytoplasm and nucleus. Is expressed in several structures, including brain; endocrine system; gut; head; and liver and biliary system. Orthologous to human WWTR1 (WW domain containing transcription regulator 1).