Substrate-specific adapter of a BCR (BTB-CUL3-RBX1) E3 ubiquitin ligase complex that acts as a regulator of ion transport in the distal nephron. Protein modification; protein ubiquitination. Component of the BCR(KLHL3) E3 ubiquitin ligase complex, at least composed of cul3 and klhl3 and rbx1.