DNA-binding protein that binds to the to a 5'-TGTACAGTGT-3' core sequence. May function as a transcriptional transactivator and transcriptional repressor (By similarity). Probably exerts its repressor effect by preventing GATA3 from binding to DNA. May play a role in regulating the differentiation and activation of helper T-cells. Homodimer (via PTB domain). Interacts with the N-terminal of FANCC. Interacts with ZBTB16 (By similarity). Interacts with GATA3. Located in nuclear speckles. Isoform 1 is testis-specific and is not expressed in lymphoid organs such as thymus or spleen. Isoform 2 is expressed in both B- and T-lymphoid cells. The C-terminal zinc finger domain functions as a transcriptional transactivator. The BTB (POZ) domain possesses repressor activity. Belongs to the krueppel C2H2-type zinc-finger protein family.