May act as an adapter protein to couple membrane receptors to intracellular signaling pathways (Probable). Core component of the CTLH E3 ubiquitin-protein ligase complex that selectively accepts ubiquitin from UBE2H and mediates ubiquitination and subsequent proteasomal degradation of the transcription factor HBP1 (PubMed:29911972). Enhances dihydrotestosterone-induced transactivation activity of AR, as well as dexamethasone-induced transactivation activity of NR3C1, but does not affect estrogen-induced transactivation (PubMed:18222118). Acts as a guanine nucleotide exchange factor (GEF) for RAN GTPase. May play an essential role in hemostasis and in maintaining microtubule dynamics with respect to both platelet shape and function (By similarity). {ECO:0000250|UniProtKB:Q6VN19, ECO:0000269|PubMed:18222118, ECO:0000269|PubMed:29911972, ECO:0000305}. This is the function of RANBP10 (RAN binding protein 10, Ensembl gene identifier ENSG00000141084).