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. 2022 Jan 28;10:787294. doi: 10.3389/fcell.2022.787294

FIGURE 2.

FIGURE 2

AURORA B localizes at multiple sites along the centromere-KT axis. (A) AURORA B kinase associates with INCENP, BOREALIN and SURVIVIN to assemble the chromosomal passenger complex (CPC). (B) The conspicuous centromeric localization of the CPC relies on the interaction of SURVIVIN and BOREALIN with either inner centromeric phospho-H3-Thr3 or KT-proximal SHUGOSHIN1/2 (SGO), respectively. H3-Thr3 is phosphorylated by HASPIN, while KNL1-associated BUB1 phosphorylates H2A-Thr120 to recruit SGO (note that nucleosomes are represented either as “H3” or “A” to distinguish between canonical H3- or CENP-A-containing nucleosomes). It has also been proposed that a pool of AURORA B is present at KTs, although the KT receptor for this pool remains unknown (“?”). Importantly, the prominent accumulation of CPC at centromeres supports prompt activation of AURORA B through trans auto-phosphorylation. Additionally, AURORA B phosphorylates INCENP to fully activate the CPC complex. Active centromeric and KT AURORA B phosphorylate critical substrates with key roles in KT-MT attachment stabilization, namely the NDC80c (N-terminal tail in NDC80), the SKAc and KNL1 (PP1-docking motif). The activity of AURORA B is likely counteracted by PP2A:B56 during early mitotic stages and by PP1 at later stages.