Transcription factor that can function as an activator or repressor depending on its binding partners, and by targeting negative regulators of cell cycle progression. Plays a critical role in early lymphocyte development, where it is essential to prevent apoptosis in lymphoid precursors, allowing them to survive in response to IL7 and undergo proper lineage commitment. Has been shown to bind to the promoters of adenovirus major late protein and cyclin D1 and activate transcription. Required for early embryonic development during gastrulation. Represses RB1 transcription; this repression can be blocked by interaction with ZBTB49 isoform 3/ZNF509S1 (PubMed:25245946). Homooligomerizes (via the BTB/POZ domain), multimerization is required for DNA binding. Interacts (via the C-terminal zinc fingers) with GIF1; the interaction results in the recruitment of MYB to the CDKN1A/p21 and CDKN1B promoters and repression of transcription. Interacts with TRAF2, interfering with the binding of UBC13 to TRAF2, and inhibiting TRAF2 E3 ligase activity. Interacts with MYC (via the C-terminal helix-loop-helix motif); the interaction inhibits ZBTB17 transactivation and growth arrest activities and renders it insoluble in the nucleus. Also interacts with HCFC1, MAGEA4 and TMPRSS11A. Interacts with BCL6; the interaction inhibits ZBTB17 transactivation activity on target genes involved in cell cycle arrest. Interacts with ZBTB49 isoform 3/ZNF509S1; this interaction blocks ZBTB17-mediated repression of RB1 (PubMed:25245946). Expressed in germinal center B-cells. Undergoes 'Lys-48'-linked polyubiquitination at Lys-397 and Lys-481 and subsequent proteasomal degradation in a TRAF2-dependent manner. Belongs to the krueppel C2H2-type zinc-finger protein family.