This is the C-terminal domain of chain A, also known as sub-unit 1, found in anaphase-promoting complex (APC/C) present in Homo sapiens. APC/C is an ubiquitin ligase that controls chromosome segregation and mitotic exit [1].

1: Atomic structure of the APC/C and its mechanism of protein ubiquitination. Chang L, Zhang Z, Yang J, McLaughlin SH, Barford D; Nature. 2015;522:450-454. PMID:26083744