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. Protein modification; protein ubiquitination. Interacts with CUL3A. Preferentially expressed in young leaves, roots and stems. Up-regulated by auxin (IAA), salicylic acid (SA), hydrogen peroxide and cold. The BTB/POZ domain mediates the interaction with some component of ubiquitin ligase complexes. Truncated N-terminus. Truncated N-terminus.