Substrate-specific adapter of a BCR (BTB-CUL3-RBX1) E3 ubiquitin ligase complex that mediates the ubiquitination of target proteins, such as NPTXR, WNK1, WNK3 and WNK4, leading most often to their proteasomal degradation (PubMed:23838290). The BCR(KLHL2) complex catalyzes ubiquitination and degradation of NPTXR (By similarity). Responsible for degradative ubiquitination of the WNK kinases WNK1, WNK3 and WNK4 (PubMed:23838290). Plays a role in the reorganization of the actin cytoskeleton (PubMed:10397770). Promotes growth of cell projections in oligodendrocyte precursors (PubMed:15715669). {ECO:0000250|UniProtKB:Q8JZP3, ECO:0000269|PubMed:10397770, ECO:0000269|PubMed:15715669, ECO:0000269|PubMed:23838290}. This is the function of KLHL2 (kelch like family member 2, ENSG00000109466).