Apc9 is one of the subunits of the anaphase-promoting complex, or cyclosome [1], which is essential for regulating entry into anaphase and exit from mitosis. The APC is a ubiquitin-protein ligase complex. All APC subunits are members of the cullin family proteins, which bind to a ring-finger subunit via a conserved cullin domain [2]. The APC is made up of four parts, the third of which is a tetratricopeptide repeat arm (TPR) that contains Apc9 [3].

1: Mass spectrometric analysis of the anaphase-promoting complex from yeast: identification of a subunit related to cullins. Zachariae W, Shevchenko A, Andrews PD, Ciosk R, Galova M, Stark MJ, Mann M, Nasmyth K; Science. 1998;279:1216-1219. PMID:9469814

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: APC-targeted RAA1 degradation mediates the cell cycle and root development in plants. Xu Y, Cao H, Chong K; Plant Signal Behav. 2010; [Epub ahead of print] PMID:20037474