Degeneracy and Function of the Ubiquitous RVXF Motif That Mediates Binding to Protein Phosphatase-1

ABSTRACTCell polarity is essential for various asymmetric cellular events, and the partitioning defective (PAR) protein PAR3 (encoded by PARD3 in mammals) plays a unique role as a cellular landmark to establish polarity. In epithelial cells, PAR3 localizes at the subapical border, such as the tight junction in vertebrates, and functions as an apical determinant. Although we know a great deal about the regulators of PAR3 localization, how PAR3 is concentrated and localized to a specific membrane domain remains an important question to be clarified. In this study, we demonstrate that ASPP2 (also known as TP53BP2), which controls PAR3 localization, links PAR3 and protein phosphatase 1 (PP1). The ASPP2–PP1 complex dephosphorylates a novel phosphorylation site, Ser852, of PAR3. Furthermore, Ser852- or Ser889-unphosphorylatable PAR3 mutants form protein clusters, and ectopically localize to the lateral membrane. Concomitance of clustering and ectopic localization suggests that PAR3 localization is a consequence of local clustering. We also demonstrate that unphosphorylatable forms of PAR3 exhibited a low molecular turnover and failed to coordinate rapid reconstruction of the tight junction, supporting that both the phosphorylated and dephosphorylated states are essential for the functional integrity of PAR3.

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Regulation and Function of the Muscle Glycogen-Targeting Subunit of Protein Phosphatase 1 (GM) in Human Muscle Cells Depends on the COOH-Terminal Region and Glycogen Content

Diabetes ◽

10.2337/diabetes.52.9.2221 ◽

2003 ◽

Vol 52 (9) ◽

pp. 2221-2226 ◽

Cited By ~ 13

Author(s):

C. Lerin ◽

E. Montell ◽

T. Nolasco ◽

C. Clark ◽

M. J. Brady ◽

...

Keyword(s):

Muscle Glycogen ◽

Protein Phosphatase ◽

Glycogen Content ◽

Muscle Cells ◽

Human Muscle ◽

Terminal Region ◽

Protein Phosphatase 1 ◽

And Function ◽

Human Muscle Cells

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Protein phosphatase 1 – targeted in many directions

Journal of Cell Science ◽

10.1242/jcs.115.2.241 ◽

2002 ◽

Vol 115 (2) ◽

pp. 241-256 ◽

Cited By ~ 22

Author(s):

Patricia T. W. Cohen

Keyword(s):

Protein Phosphatase ◽

Protein Phosphatase 1 ◽

Binding Motif ◽

Cellular Functions ◽

Regulatory Subunits ◽

Specific Location ◽

Hydrophobic Groove ◽

Intracellular Signals ◽

Small Hydrophobic ◽

Rvxf Motif

Protein phosphatase 1 (PP1) is a major eukaryotic protein serine/threonine phosphatase that regulates an enormous variety of cellular functions through the interaction of its catalytic subunit (PP1c) with over fifty different established or putative regulatory subunits. Most of these target PP1c to specific subcellular locations and interact with a small hydrophobic groove on the surface of PP1c through a short conserved binding motif – the RVxF motif – which is often preceded by further basic residues. Weaker interactions may subsequently enhance binding and modulate PP1 activity/specificity in a variety of ways. Several putative targeting subunits do not possess an RVxF motif but nevertheless interact with the same region of PP1c. In addition, several ‘modulator’ proteins bind to PP1c but do not possess a domain targeting them to a specific location. Most are potent inhibitors of PP1c and possess at least two sites for interaction with PP1c, one of which is identical or similar to the RVxF motif.Regulation of PP1c in response to extracellular and intracellular signals occurs mostly through changes in the levels, conformation or phosphorylation status of targeting subunits. Understanding of the mode of action of PP1c complexes may facilitate development of drugs that target particular PP1c complexes and thereby modulate the phosphorylation state of a very limited subset of proteins.

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Molecular Investigations of the Structure and Function of the Protein Phosphatase 1−Spinophilin−Inhibitor 2 Heterotrimeric Complex

Biochemistry ◽

10.1021/bi101774g ◽

2011 ◽

Vol 50 (7) ◽

pp. 1238-1246 ◽

Cited By ~ 26

Author(s):

Barbara Dancheck ◽

Michael J. Ragusa ◽

Marc Allaire ◽

Angus C. Nairn ◽

Rebecca Page ◽

...

Keyword(s):

Protein Phosphatase ◽

Structure And Function ◽

Protein Phosphatase 1 ◽

And Function

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Protein phosphatase 1 regulates assembly and function of the β-catenin degradation complex

The EMBO Journal ◽

10.1038/sj.emboj.7601607 ◽

2007 ◽

Vol 26 (6) ◽

pp. 1511-1521 ◽

Cited By ~ 81

Author(s):

Wen Luo ◽

Annita Peterson ◽

Benjamin A Garcia ◽

Gary Coombs ◽

Bente Kofahl ◽

...

Keyword(s):

Protein Phosphatase ◽

Protein Phosphatase 1 ◽

And Function

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The translation initiation factor eIF2β is an interactor of protein phosphatase-1

Biochemical Journal ◽

10.1042/bj20060758 ◽

2006 ◽

Vol 400 (2) ◽

pp. 377-383 ◽

Cited By ~ 13

Author(s):

Paulina Wakula ◽

Monique Beullens ◽

Aleyde van Eynde ◽

Hugo Ceulemans ◽

Willy Stalmans ◽

...

Keyword(s):

Translation Initiation ◽

Protein Phosphatase ◽

Translation Initiation Factor ◽

Site Directed Mutagenesis ◽

Protein Phosphatase 1 ◽

Initiation Factor ◽

Homology Search ◽

Initiation Factors ◽

Initiation Of Translation ◽

Rvxf Motif

It is reasonably well understood how the initiation of translation is controlled by reversible phosphorylation of the eukaryotic translation initiation factors eIF2α, eIF2Bϵ and eIF4E. Other initiation factors, including eIF2β, are also established phosphoproteins but the physiological impact of their phosphorylation is not known. Using a sequence homology search we found that the central region of eIF2β contains a putative PP1-(protein phosphatase-1) binding RVxF-motif. The predicted eIF2β-PP1 interaction was confirmed by PP1 binding and co-immunoprecipitation assays on cell lysates as well as with the purified components. Site-directed mutagenesis showed that eIF2β contains, in addition to an RVxF-motif, at least one other PP1-binding site in its C-terminal half. eIF2β functioned as an inhibitor for the dephosphorylation of glycogen phosphorylase and Ser51of eIF2α by PP1, but did not affect the dephosphorylation of Ser464 of eIF2Bϵ by this phosphatase. Strikingly, eIF2β emerged as an activator of its own dephosphorylation (Ser2, Ser67, Ser218) by associated PP1, since the substrate quality of eIF2β was decreased by the mere mutation of its RVxF-motif. These results make eIF2β an attractive candidate substrate for associated PP1 in vivo. The overexpression of wild-type eIF2β or eIF2β with a mutated RVxF-motif did not differentially affect the rate of translation, indicating that the binding of PP1 is not rate-limiting for translation under basal conditions.

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Biogenesis and activity regulation of protein phosphatase 1

Biochemical Society Transactions ◽

10.1042/bst20160154 ◽

2017 ◽

Vol 45 (1) ◽

pp. 89-99 ◽

Cited By ~ 38

Author(s):

Iris Verbinnen ◽

Monica Ferreira ◽

Mathieu Bollen

Keyword(s):

Protein Phosphatase ◽

Protein Phosphatase 1 ◽

Interacting Proteins ◽

Subcellular Targeting ◽

Substantial Fraction ◽

Short Linear Motifs ◽

Specific Subset ◽

Linear Motifs ◽

And Function ◽

And Control

Protein phosphatase 1 (PP1) is expressed in all eukaryotic cells and catalyzes a substantial fraction of phosphoserine/threonine dephosphorylation reactions. It forms stable complexes with PP1-interacting proteins (PIPs) that guide the phosphatase throughout its life cycle and control its fate and function. The diversity of PIPs is huge (≈200 in vertebrates), and most of them combine short linear motifs to form large and unique interaction interfaces with PP1. Many PIPs have separate domains for PP1 anchoring, PP1 regulation, substrate recruitment and subcellular targeting, which enable them to direct associated PP1 to a specific subset of substrates and mediate acute activity control. Hence, PP1 functions as the catalytic subunit of a large number of multimeric holoenzymes, each with its own subset of substrates and mechanism(s) of regulation.

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