Enables nuclear receptor coactivator activity. Involved in endosome to lysosome transport and protein monoubiquitination. Located in endosome membrane and nucleus. Human ortholog(s) of this gene implicated in breast cancer; breast carcinoma; cervix carcinoma; endometrial adenocarcinoma; and prostate cancer. Orthologous to human TSG101 (tumor susceptibility 101). [provided by Alliance of Genome Resources, Apr 2022]