Substrate-specific adapter of a BCR (BTB-CUL3-RBX1) E3 ubiquitin-protein ligase complex required for synaptic transmission (By similarity). The BCR(KCTD13) E3 ubiquitin ligase complex mediates the ubiquitination of RHOA, leading to its degradation by the proteasome, thereby regulating the actin cytoskeleton and promoting synaptic transmission (PubMed:29088697). Increased levels of RHOA. N ochange in brain size or neural progenitor cell proliferation is observed. Belongs to the BACURD family. According to a first report, morpholino-mediated knockdown of kctd13 leads to increased brain size and cell proliferation (PubMed:22596160). However, it was later shown that deletion of kctd13 does not cause any change in brain size or cell proliferation (PubMed:29088697). Experimental conditions used may explain discrepancies. A possible explanation being that morpholinos used in the first study, may have affected off-targets.