Substrate recognition component of a DCX (DDB1-CUL4-X-box) E3 protein ligase complex that mediates the ubiquitination and subsequent proteasomal degradation of target proteins. Has an essential role in mediating growth by negatively regulating insulin signaling. It also has a role in maintaining presynaptic function in the neuromuscular junction synapses of third-instar larvae. Protein modification; protein ubiquitination. Likely a component of a DCX (DDB1-CUL4-X-box) protein ligase complex (By similarity). May interact with pic/DDB1 (By similarity). Ubiquitinated. Belongs to the CRBN family.