Core component of a Cul9-RING ubiquitin-protein ligase complex, a complex that mediates ubiquitination and subsequent degradation of BIRC5 and is required to maintain microtubule dynamics and genome integrity. Acts downstream of the 3M complex, which inhibits CUL9 activity, leading to prevent ubiquitination of BIRC5 (PubMed:24793696). Cytoplasmic anchor protein in p53/TP53-associated protein complex. Regulates the subcellular localization of p53/TP53 and subsequent function (PubMed:12526791, PubMed:17332328). Part of a Cul9-RING complex at least composed of CUL9 and RBX1. Interacts with CUL7: interaction with CUL7 component of the 3M complex leads to inhibition of CUL9 activity. The CUL7-CUL9 heterodimer seems to interact specifically with TP53. Forms a complex with p53/TP53 in the cytoplasm of unstressed cells. Interacts with UBCH7 and UBCH8. Ubiquitously expressed in all tissues with highest expression in testis brain and kidney. The IBR domain is required for interaction with UBCH7 and UBCH8. In vitro, self-ubiquitination in the presence of E1, E2 and ubiquitin. Neddylated. Belongs to the cullin family. Intron retention. Intron retention.