The multi-PDZ domain protein MUPP1 is a cytoplasmic ligand for the membrane-spanning proteoglycan NG2

Barritt, Diana S.; Pearn, Michael T.; Zisch, Andreas H.; Lee, Siu Sylvia; Javier, Ronald T.; Pasquale, Elena B.; Stallcup, William B.

doi:10.1002/1097-4644(20001101)79:2<213::aid-jcb50>3.0.co;2-g

Cited by 92 publications

(63 citation statements)

References 56 publications

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“…Furthermore, the ¢rst PDZ of MUPP1 is a member of the most abundant group (G,H); therefore it should bind to class I motifs. In contrast, our computer-aided analysis [1] and two hybrid (in vitro) and co-immunoprecipitation (in vivo) assays [4] indicate a preference of MUPP1-1 PDZ domain for class II ligands, such as NG2 proteoglycan. Another example is CIPP-3 PDZ domain that is classi¢ed as (G,p) and therefore it should prefer peptides related to the consensus (8Dx*); in contrast, it interacts with Kir4.2 channel and NR2 (type A-B-C-D) receptors that have class I extremities [5].…”

contrasting

confidence: 61%

PDZ domains: troubles in classification

Vaccaro

Dente

2002

FEBS Letters

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Classi¢cation of protein interaction domains on the basis of the chemical characteristics of binding pocket residues is a di¤cult task, because multiple contact positions are usually involved in the recognition speci¢city mechanism. On the other hand, target peptides may be classi¢ed according to the (few) speci¢c residues that constitute the binding motif, through analysis of molecular repertoires (libraries of synthetic peptides; phage display; two hybrid, etc.) that allow identifying collections of di¡erent ligands.We have recently pointed out that, in order to characterize PDZ domains and to infer their binding speci¢city, it is necessary to exploit computational procedures, which simultaneously take into account all the contact positions of the domain binding pocket and the corresponding residues of the ligand [1]. PDZ domains are protein interaction modules that recognize and bind the C-terminal four residues of their target. The solution of X-ray crystallographic structure of PDZ domains complexed with their peptide ligands reveals at least 23 contact positions, whose interacting atoms are at a distance shorter than the sum of the van der Waals radii (r) +3 A î .Some of these positions contain residues that are highly conserved in the PDZ domain family: for example thè GLGF' loop and a positively charged residue that accommodate the terminal carboxylate group. The majority of the PDZ domains (identi¢ed in the proteome up to now) recognize ligands of class I (Table 1). These PDZ domains are provided with a hydrophilic pocket, where residues of the LB strand and of the KB helix (in particular a histidine, highly conserved at position KB1) are involved in contacting the peptide ligand.Most of the remaining PDZ domains recognize a varied class of ligand peptides, characterized by aromatic or hydrophobic residues at position P 32 . Even residues mimicking part of a hydrophobic moiety at position P 32 (such as the arginine at P 32 of the peptide ligand in the crystallized structure of hCASK) can be accommodated in the large hydrophobic pocket that characterizes PDZ domains binding to class II peptides [2]. Main determinants of the binding, as derived from the contacts in the crystal structure, are residues at LB5, KB1 and KB3 positions.Bezprozvanny and Maximov have recently proposed a classi¢cation of the PDZ domains listed in the SMART Website, based upon the type of residues present in only two contact positions^LB5 and KB1^of the binding pocket [3]. By grouping the couples of residues on the basis of their polarity and/or bulkiness, they de¢ned 25 groups and correlated them to experimentally determined ligands. Unfortunately, ligand sequences are available only for nine out of 25 groups and, while the ¢rst group (G,H) is enforced by the presence of 68 PDZ domains (those binding to class I motifs), the others are less clearly determined. Two of them (G,n) and (a,p) do not correspond to known PDZ

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contrasting

confidence: 61%

PDZ domains: troubles in classification

Vaccaro

Dente

2002

FEBS Letters

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“…Plasmid Constructions and Cell Culture-The GW1-HA-MUPP1 plasmid containing the coding region of the rat MUPP1 as well as GST fusion constructs expressing PDZ1-3, PDZ4-5, PDZ6, PDZ7, or PDZ8-9 were a gift from Dr. Javier and have been described elsewhere (22,23). GST fusion constructs containing PDZ9, PDZ10, or PDZ11-12 were a gift from Dr. Mancini (24).…”

Section: Methodsmentioning

confidence: 99%

“…Receptor immunoprecipitation was done on supernatant by the anti-FLAG M2 antibody (Sigma) preadsorbed on Protein G. Immunoadsorbed material was pelleted by centrifugation, submitted to SDS-PAGE, and transferred to nitrocellulose. Immunoblot analysis was carried out with the polyclonal anti-MUPP1 antiserum at 1:20,000 dilution (a gift from Dr. Javier) (22,23) or the polyclonal anti-FLAG antibody (Sigma), and immunoreactivity was revealed using a goat anti-rabbit secondary antibody coupled to horseradish peroxidase and the ECL chemiluminescent reagent (Amersham Biosciences).…”

Section: Methodsmentioning

confidence: 99%

The PDZ Protein Mupp1 Promotes Gi Coupling and Signaling of the Mt1 Melatonin Receptor

Guillaume

Daulat

Maurice

et al. 2008

Journal of Biological Chemistry

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The concept of organized networks has emerged in the field of cellular signaling in the last few years. Assembling the different partners in close proximity optimizes the spatial and temporal organization and the specificity of the cellular response. The assembly of these multimolecular complexes occurs through the interaction of modular domains recognizing their target counterparts. PDZ domains are widely spread modules exhibiting this function. Data bank exploration with SMART (1) identifies 584 PDZ domains in 328 different proteins in the human genome.G protein-coupled receptors (GPCRs) 5 constitute the largest family of membrane receptors, and many of the more than 750 members have been shown to interact with PDZ domain-containing proteins, either constitutively or upon agonist activation (2). Binding of PDZ proteins to GPCRs has been reported to primarily regulate subcellular localization, trafficking, and stability of receptors (3). For instance, binding of MUPP1 and syntrophins to the ␥-aminobutyric acid type B (GABA B ) receptor and the ␣ 1D -adrenergic receptor, respectively, significantly increases receptor stability (4, 5). In other cases, PDZ scaffolds determine the subcellular localization of GPCRs (6) and receptor endocytosis as shown for PSD-95 and the 5-HT 2A serotonin and ␤ 1 -adrenergic receptors (7,8). PDZ proteins, such as NHERF and hScrib, are also important for the recycling of receptors to the cell surface (9 -11).Binding of PDZ proteins to GPCRs also modulates receptor signaling by assembling proteins involved in signal transduction. NHERF family proteins are known to regulate the activity of the Na ϩ /H ϩ exchanger through association with NHERF-1 (12) and to form a ternary complex with phospholipase C␤3 and GPCRs, which enhances the signaling efficiency of the receptor-mediated activation of the phospholipase C␤/Ca 2ϩ pathway (13-15). Binding of GIPC (GAIP-interacting protein, COOH terminus) to the COOH terminus of the D3 dopamine and the ␤ 1 -adrenergic receptor (16) decreased G␣ i -mediated signaling of these receptors most likely through RGS19, which binds to GIPC (17). Further examples of PDZ scaffolds that regulate GPCR signaling include a ternary complex formation around the PDZ scaffold MAGI-3, which binds to the GPCR frizzled-4 and Ltap to regulate the JNK signaling cascade (18), as well as PDZ-domain-containing Rho guanine nucleotide exchange factors that interact with lysophosphatidic acid 1 and 2 receptors to activate RhoA (19).

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“…MUPP1 was initially identified as a protein that interacts with the COOH terminus of the serotonin 5-hydroxytryptamine type 2C receptor (44,45,52). This protein was also reported to be associated with c-Kit (50), the membrane-spanning proteoglycan NG2 (53), and adenovirus E4-ORF1 and high-risk papillomavirus type 18 E6 oncoproteins (54) but has not been well characterized, especially in terms of its subcellular localization. In this study, we generated a pAb specific for MUPP1, and by immunofluorescence as well as immunoelectron microscopy we concluded that in simple epithelial cells MUPP1 is concentrated at TJs, favoring the in vivo interaction between MUPP1 and claudins.…”

Section: Generation and Evaluation Of Anti-mupp1 Pab-to Exam-mentioning

confidence: 99%

Multi-PDZ Domain Protein 1 (MUPP1) Is Concentrated at Tight Junctions through Its Possible Interaction with Claudin-1 and Junctional Adhesion Molecule

Hamazaki¹,

Itoh²,

Sasaki³

et al. 2002

Journal of Biological Chemistry

320

235

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Claudins, most of which end in valine at their COOH termini, constitute tight junction (TJ) strands, suggesting that TJ strands strongly attract PDZ-containing proteins. Indeed, ZO-1, -2, and -3, each of which contains three PDZ domains, were shown to directly bind to claudins. Using the yeast two-hybrid system, we identified ZO-1 and MUPP1 (multi-PDZ domain protein 1) as binding partners for the COOH terminus of claudin-1. MUPP1 has been identified as a protein that contains 13 PDZ domains, but it has not been well characterized. In vitro binding assays with recombinant MUPP1 confirmed the interaction between MUPP1 and claudin-1 and identified PDZ10 as the responsible domain for this interaction. A polyclonal antibody specific for MUPP1 was then generated. Immunofluorescence confocal microscopy as well as immunoelectron microscopy with this antibody revealed that in polarized epithelial cells MUPP1 was exclusively concentrated at TJs. Furthermore, in vitro binding and transfection experiments showed that junctional adhesion molecule, another TJ adhesion molecule, also bound to the PDZ9 domain of MUPP1. These findings suggested that MUPP1 is concentrated at TJs in epithelial cells through its binding to claudin and junctional adhesion molecule and that it may function as a multivalent scaffold protein that recruits various proteins to TJs. Tight junctions (TJs)1 constitute the epithelial and endothelial junctional complex together with adherens junctions and desmosomes and are located at the most apical part of the complex (1). TJs have dual barrier and fence roles. They create the primary barrier to the diffusion of solutes through the paracellular pathway and maintain cell polarity as a boundary between the apical and basolateral plasma membrane domains (1-5). On ultrathin section electron microscopy, TJs appear as a series of discrete sites of apparent fusion, involving the outer leaflet of the plasma membranes of adjacent cells (1). On freeze-fracture electron microscopy, TJs appear as a set of continuous, anastomosing intramembranous particle strands (TJ strands) (6, 7).The molecular architecture of TJs has been unraveled rapidly in recent years. Two distinct types of integral membrane proteins, occludin and claudins, have been identified as constituents of TJ strands (8 -10). Both occludin and claudins bear four transmembrane domains but do not show any sequence similarity with each other. Claudins and occludin are thought to constitute the backbone of TJ strands and to modulate some functions of TJs, respectively (5, 10 -15). Claudins comprise a multigene family consisting of more than 20 members (9, 10, 16 -19). It was recently shown that heterogeneous claudin species (and also occludin) are co-polymerized to form individual TJ strands as heteropolymers and that between adjacent cells claudin molecules adhere with each other in both homotypic and heterotypic manners except in some combinations (20,21). In addition to claudins and occludin, another type of integral membrane protein, JAM (junctional adhesi...

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The multi-PDZ domain protein MUPP1 is a cytoplasmic ligand for the membrane-spanning proteoglycan NG2

Cited by 92 publications

References 56 publications

PDZ domains: troubles in classification

PDZ domains: troubles in classification

The PDZ Protein Mupp1 Promotes Gi Coupling and Signaling of the Mt1 Melatonin Receptor

Multi-PDZ Domain Protein 1 (MUPP1) Is Concentrated at Tight Junctions through Its Possible Interaction with Claudin-1 and Junctional Adhesion Molecule

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