Zinc-finger proteins contain DNA-binding domains and have a wide variety of functions, most of which encompass some form of transcriptional activation or repression. The majority of zinc-finger proteins contain a Krüppel-type DNA binding domain and a KRAB domain, which is thought to interact with KAP1, thereby recruiting histone modifying proteins. Zinc finger and BTB domain-containing protein 25 (ZBTB25), also known as ZNF46 or KUP, is a 435 amino acid member of the Krüppel C2H2-type zinc-finger protein family. Localized to the nucleus and expressed mainly in hematopoietic cells and testis, ZBTB25 contains a BTB domain, also known as a POZ domain, which inhibits DNA binding and mediates homotypic and heterotypic dimerization. Characteristics of the BTB domain suggest that ZBTB25 functions as a transcription regulator.