Apc1 is the largest of the subunits of the anaphase-promoting complex or cyclosome. The anaphase-promoting complex is a multiprotein subunit E3 ubiquitin ligase complex that controls segregation of chromosomes and exit from mitosis in eukaryotes [1,2]. Infection of human fibroblasts with human cytomegalovirus (HCMV) leads to cell cycle dysregulation, which is associated with the inactivation of the anaphase-promoting complex [3]. Apc1 consists of a N-terminal WD40 beta-propeller domain, a middle domain (Mid-N), a PC domain and a C-terminal domain (Mid-C) that coalesces with Mid-N to form Apc1Mid which connects Apc1-WD40 with Apc1-PC and comprises an alpha-solenoid capped by a beta-sandwich [4,5]. The N-terminal domain is essential for APC/C catalytic activity as it mediates the coactivator-induced conformational change of the APC/C which promotes UbcH10 binding [4].

1: Characterisation of the human APC1, the largest subunit of the anaphase-promoting complex. Jorgensen PM, Graslund S, Betz R, Stahl S, Larsson C, Hoog C; Gene. 2001;262:51-59. PMID:11179667

2: The anaphase promoting complex/cyclosome: a machine designed to destroy. Peters JM; Nat Rev Mol Cell Biol. 2006;7:644-656. PMID:16896351

3: Accumulation of substrates of the anaphase-promoting complex (APC) during human cytomegalovirus infection is associated with the phosphorylation of Cdh1 and the dissociation and relocalization of APC subunits. Tran K, Mahr JA, Choi J, Teodoro JG, Green MR, Spector DH; J Virol. 2008;82:529-537. PMID:17942546

4: WD40 domain of Apc1 is critical for the coactivator-induced allosteric transition that stimulates APC/C catalytic activity. Li Q, Chang L, Aibara S, Yang J, Zhang Z, Barford D; Proc Natl Acad Sci U S A. 2016;113:10547-10552. PMID:27601667

5: 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