Enables phosphatase binding activity and ubiquitin ligase-substrate adaptor activity. Involved in protein ubiquitination and ubiquitin-dependent protein catabolic process via the C-end degron rule pathway. Part of Cul4A-RING E3 ubiquitin ligase complex. Is active in Cul4-RING E3 ubiquitin ligase complex. [provided by Alliance of Genome Resources, Apr 2022]