Identification of Multiple Binding Partners for the Amino-terminal Domain of Synapse-associated Protein 97

Karnak, David; Lee, Seonok; Margolis, Ben

doi:10.1074/jbc.m208781200

Cited by 56 publications

(59 citation statements)

References 30 publications

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“…Consistent with earlier reports, mixing experiments using 15 N-labeled recombinant proteins showed that the L27S of SAP97 and L27N of mLin-2 formed a stable heteromeric complex and that the L27 domain of mLin-7 and L27C of mLin-2 formed another heteromeric complex 3,[13][14][15] (data not shown). We chose the L27S-L27N pair for further structural analysis owing to the better spectral quality of this complex ( Supplementary Fig.…”

supporting

confidence: 91%

The tetrameric L27 domain complex as an organization platform for supramolecular assemblies

Feng

Long

Fan

et al. 2004

Nat Struct Mol Biol

101

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Clustering and asymmetric distribution of receptors, ion channels and associated protein complexes are essential to the polarity of neurons and epithelial cells. Such asymmetric targeting of large molecular assemblies is thought to be governed in part by modular scaffold proteins. L27 domain, initially identified in the C. elegans Lin-2 and Lin-7 proteins, is a protein interaction module that exists in a large family of scaffold proteins 1 . Formation of the trimeric Lin-2-Lin-7-Lin-10 complex requires L27 domains 2,3 and has a central role in targeting receptor tyrosine kinase Let-23 signalsome to the basolateral surface of vulval precursor cells 4,5 . Mutations in Lin-2, Lin-7 or Lin-10 lead to a vulvaless phenotype, presumably by mistargeting of 5). The mammalian orthologs of Lin-2, Lin-7 and Lin-10 are known as mammalian Lin-2 (mLin-2)/CASK, mLin-7/Velis/Mals and mLin-10/X11α/Mint1, respectively 2,6-9 . The mLin-2-mLin-7-mLin-10 tripartite complex has also been observed in the brain 2,6 , and this evolutionarily conserved protein complex has been implicated in the targeting of NMDA receptors and β-catenin assemblies to membrane subdomains in epithelia and neurons 10,11 .A bioinformatics survey reveals that L27 domain-containing proteins are invariably scaffold proteins containing multiple proteinprotein interaction domains without intrinsic enzyme activities 12 . For example, SAP97 and mLin-2/CASK, which are members of a subset of membrane-associated guanylate kinases (MAGUKs), contain one and two L27 domains, respectively, in addition to their PDZ, SH3 and guanylate kinase-like domains. The N-terminal L27 domain of SAP97 can form specific heteromeric complexes with the N-terminal L27 domain of mLin-2, Dlg2 and Dlg3, respectively 3,13,14 . The C-terminal L27 domain of mLin-2 specifically binds to the L27 domain of 15). The discovery of L27 domains as specific protein-protein interaction modules capable of forming heteromeric complexes suggests that L27 domains can integrate multiple scaffold proteins into supramolecular assemblies 1,3,13,15,16 . However, the molecular basis of the L27 domain-mediated protein assembly formation remains unclear. The structures of isolated L27 domains and their cognate heteromeric complexes are not known.Here we show that the L27 domain of SAP97 and the N-terminal L27 domain of mLin-2 form a heterotetrameric complex. The structure of the SAP97-mLin-2 L27 complex was solved by NMR spectroscopy. The structure of the complex, together with data derived from various biochemical studies, establishes the roles of specific residues in the formation of the L27 heterotetrameric complex. The structure of the SAP97-mLin-2 L27 complex further suggests a mechanistic model for polymerization of L27 domain scaffold proteins. RESULTS L27 domains form specific heterotetrameric complexesWe first characterized the structural properties of the isolated L27 domains of SAP97 (referred to as L27S below), mLin-7, the N-terminal L27 domain (referred to as L27N below), and the C-terminal L27 domain (ref...

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supporting

confidence: 91%

The tetrameric L27 domain complex as an organization platform for supramolecular assemblies

Feng

Long

Fan

et al. 2004

Nat Struct Mol Biol

101

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“…Thus, these studies revealed that the two cognate pairs of L27 heterodimers assemble into heterotrimers in a tandem L27 domain-mediated cooperative mode. It was reported that MPP3(DLG3) and MPP2(DLG2), two Mals-binding proteins, bind DLG1/synapse-associated protein 97 (SAP97) and require both the L27N and the L27C domains of MPP3 and MPP2, respectively (35), indicating that these heterotrimers may also form through the tandem L27 domainmediated cooperative assembly mode.…”

Section: Discussionmentioning

confidence: 99%

Structure of an L27 Domain Heterotrimer from Cell Polarity Complex Patj/Pals1/Mals2 Reveals Mutually Independent L27 Domain Assembly Mode

Zhang

Yang

Wang

et al. 2012

Journal of Biological Chemistry

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Background: Tandem L27 domains are important for multidomain proteins to assemble into supramolecular complexes for cell polarity regulation. Results: Tandem L27 domain-mediated tripartite Patj/Pals1/Mals2 and DLG1/CASK/Mals2 complexes form in a mutually independent assembly mode. Conclusion:The mutually independent assembly mode may be a novel mechanism for tandem L27 domain-mediated, tripartite complex formation. Significance: These findings reveal the distinct mechanism of tandem L27 domain-mediated assembly of obligate supramolecular complexes.

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“…They probably do not interact directly with the channels, because the PDZ domains of these proteins will not recognize class I PDZ binding motifs, but like CASK, may be recruited by SAP97 or Veli (18). Dlg2 and Dlg3 recently were shown to bind to SAP97 (70), and these proteins contain L27 domains, which may interact with Veli proteins (27,37). No direct binding partners for the PDZ domains of Dlg2, Dlg3, and Pals2 have been described to date.…”

Section: Fig 6 Syntrophin Associates With Kir2 Channels In Vivo Amentioning

confidence: 99%

Protein Trafficking and Anchoring Complexes Revealed by Proteomic Analysis of Inward Rectifier Potassium Channel (Kir2.x)-associated Proteins

Leonoudakis

Conti

Anderson

et al. 2004

Journal of Biological Chemistry

194

148

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Inward rectifier potassium (Kir) channels play important roles in the maintenance and control of cell excitability. Both intracellular trafficking and modulation of Kir channel activity are regulated by protein-protein interactions. We adopted a proteomics approach to identify proteins associated with Kir2 channels via the channel C-terminal PDZ binding motif. Detergent-solubilized rat brain and heart extracts were subjected to affinity chromatography using a Kir2.2 C-terminal matrix to purify channel-interacting proteins. Proteins were identified with multidimensional high pressure liquid chromatography coupled with electrospray ionization tandem mass spectrometry, N-terminal microsequencing, and immunoblotting with specific antibodies. We identified eight members of the MAGUK family of proteins (SAP97, PSD-95, Chapsyn-110, SAP102, CASK, Dlg2, Dlg3, and Pals2), two isoforms of Veli (Veli-1 and Veli-3), Mint1, and actin-binding LIM protein (abLIM) as Kir2.2-associated brain proteins. From heart extract purifications, SAP97, CASK, Veli-3, and Mint1 also were found to associate with Kir2 channels. Furthermore, we demonstrate for the first time that components of the dystrophin-associated protein complex, including ␣1-, ␤1-, and ␤2-syntrophin, dystrophin, and dystrobrevin, interact with Kir2 channels, as demonstrated by immunoaffinity purification and affinity chromatography from skeletal and cardiac muscle and brain. Affinity pull-down experiments revealed that Kir2.1, Kir2.2, Kir2.3, and Kir4.1 all bind to scaffolding proteins but with different affinities for the dystrophin-associated protein complex and SAP97, CASK, and Veli. Immunofluorescent localization studies demonstrated that Kir2.2 co-localizes with syntrophin, dystrophin, and dystrobrevin at skeletal muscle neuromuscular junctions. These results suggest that Kir2 channels associate with protein complexes that may be important to target and traffic channels to specific subcellular locations, as well as anchor and stabilize channels in the plasma membrane.

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Identification of Multiple Binding Partners for the Amino-terminal Domain of Synapse-associated Protein 97

Cited by 56 publications

References 30 publications

The tetrameric L27 domain complex as an organization platform for supramolecular assemblies

The tetrameric L27 domain complex as an organization platform for supramolecular assemblies

Structure of an L27 Domain Heterotrimer from Cell Polarity Complex Patj/Pals1/Mals2 Reveals Mutually Independent L27 Domain Assembly Mode

Protein Trafficking and Anchoring Complexes Revealed by Proteomic Analysis of Inward Rectifier Potassium Channel (Kir2.x)-associated Proteins

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