Summary Atypical protein kinase C (aPKC) is a key apical-basal polarity determinant and Par complex component. It is recruited by Par3/Baz (Bazooka in Drosophila) into epithelial apical domains through high-affinity interaction. Paradoxically, aPKC also phosphorylates Par3/Baz, provoking its relocalization to adherens junctions (AJs). We show that Par3 conserved region 3 (CR3) forms a tight inhibitory complex with a primed aPKC kinase domain, blocking substrate access. A CR3 motif flanking its PKC consensus site disrupts the aPKC kinase N lobe, separating P-loop/αB/αC contacts. A second CR3 motif provides a high-affinity anchor. Mutation of either motif switches CR3 to an efficient in vitro substrate by exposing its phospho-acceptor site. In vivo, mutation of either CR3 motif alters Par3/Baz localization from apical to AJs. Our results reveal how Par3/Baz CR3 can antagonize aPKC in stable apical Par complexes and suggests that modulation of CR3 inhibitory arms or opposing aPKC pockets would perturb the interaction, promoting Par3/Baz phosphorylation.
aPKC Inhibition by Par3 CR3 Flanking Regions Controls Substrate Access and Underpins Apical-Junctional Polarization
E. Soriano,M. E. Ivanova,G. Fletcher,P. Riou,P. Knowles,K. Barnouin,A. Purkiss,B. Kostelecky,P. Saiu,M. Linch,A. Elbediwy,S. Kjær,N. O'Reilly,A. Snijders,P. Parker,B. Thompson,N. McDonald
Published 2016 in Developmental Cell
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- Publication year
2016
- Venue
Developmental Cell
- Publication date
2016-08-22
- Fields of study
Biology, Medicine
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Semantic Scholar, PubMed
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