BTB (Broad-Complex, Tramtrack and Bric a brac) /POZ (poxvirus and zinc finger) domain found in plant regulatory proteins, NPR1-4, and similar proteins
NPR1 and NPR2 are essential for pathogenicity and the utilization of many nitrogen sources. NPR1 is also called nitrogen pathogenicity regulation protein NPR1, non-inducible immunity protein 1 (Nim1), nonexpresser of PR genes 1, or salicylic acid insensitive 1 (Sai1). It acts as a transcription coactivator that plays dual roles in regulating plant immunity. NPR3 and NPR4 are involved in negative regulation of defense responses against pathogens in plant. NPR proteins contain a BTB domain, DUF3420, ankyrin (ANK) repeats, and a conserved C-terminal domain. The BTB/POZ domain is a common protein-protein interaction motif of about 100 amino acids.