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. The BTB/POZ-like domain may mediate the interaction with some component of ubiquitin ligase complexes.