May act as a substrate-specific adapter of an E3 ubiquitin-protein ligase complex (CUL3-RBX1-BTB) which mediates the ubiquitination and subsequent proteasomal degradation of target proteins (By similarity). Involved in the regulation of basal defense responses against pathogens. Protein modification; protein ubiquitination. Interacts with TGA2, TGA3, TGA5 and TGA6. Interacts with TGA2 in vivo in the nucleus. Up-regulated following pathogen challenge or salicylic acid (SA) treatment. The BTB/POZ domain mediates the interaction with some component of ubiquitin ligase complexes. Elevated PR-1 expression level and enhanced resistance to Hyaloperonospora parasitica.