A small molecule anaphase-promoting complex/cyclosome (APC/C) inhibitor that stabilizes APC/C substrates in mitotic Xenopus extracts. TAME binds to APC and prevents its activation by Cdc20 and Cdh1. In the absence of APC substrates, TAME ejects Cdc20 from the APC by promoting Cdc20 autoubiquitination in its N-terminal region. TAME also stabilizes cyclin B1 by prematurely terminating ubiquitination.