Abstract
Scribble, a member of the LAP protein family, contributes to the apicobasal polarity (ABP) of epithelial cells. The LAP-unique region of these proteins, which is essential and sufficient for ABP, includes a conserved Leucine-Rich Repeat (LRR) domain. The major binding partners of this region that could regulate ABP remain unknown. Here, using proteomics, native gel electrophoresis, and site-directed mutagenesis, we show that the concave surface of LRR domain in Scribble participates in three types of mutually exclusive interactions—(i) homodimerization, serving as an auto-inhibitory mechanism; (ii) interactions with a diverse set of polarity proteins, such as Llgl1, Llgl2, EPB41L2, and EPB41L5, which produce distinct multiprotein complexes; and (iii) a direct interaction with the protein phosphatase, PP1. Analogy with the complex between PP1 and LRR domain of SDS22, a well-studied PP1 regulator, suggests that the Scibble-PP1 complex stores a latent form of PP1 in the basolateral cell cortex. Such organization may generate a dynamic signaling network wherein PP1 could be dispatched from the complex with Scribble to particular protein ligands, achieving fast dephosphorylation kinetics.
Original language | English (US) |
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Article number | 101289 |
Journal | Journal of Biological Chemistry |
Volume | 297 |
Issue number | 5 |
DOIs | |
State | Published - Nov 1 2021 |
Funding
Acknowledgments—Sequencing, Flow Cytometry, Confocal microscopy were performed at the Genetic Medicine, Flow Cytometry, Advanced Microscopy Centers. Proteomics analysis was performed by the Northwestern Proteomics Core Facility, supported by NCI CCSG P30 CA060553 awarded to the Robert H Lurie Comprehensive Cancer Center, instrumentation award (S10OD025194) from NIH Office of Director, and the National Resource for Translational and Developmental Proteomics supported by P41 GM108569. Point mutants were constructed by Dr Oskar Laur (DNA Custom Cloning, Inc). The authors declare no competing financial interests. Funding and additional information—The work was supported by grants from the National Institutes of Health: AR44016 and AR057992 (to S. M. T.) and GM0113922 (to B. J. M.). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
ASJC Scopus subject areas
- Molecular Biology
- Biochemistry
- Cell Biology