title: Syntenin-1 is a new component of tetraspanin-enriched microdomains: mechanisms and consequences of the interaction of syntenin-1 with CD63.
abstract: Tetraspanins are clustered in specific microdomains (named tetraspanin-enriched microdomains, or TERM) in the plasma membrane and regulate the functions of associated transmembrane receptors, including integrins and receptor tyrosine kinases. We have identified syntenin-1, a PDZ domain-containing protein, as a new component of TERM and show that syntenin-1 specifically interacts with the tetraspanin CD63. Detailed biochemical and heteronuclear magnetic resonance spectroscopy (NMR) studies have demonstrated that the interaction is mediated by the C-terminal cytoplasmic region of the tetraspanin and the PDZ domains of syntenin-1. Upon interaction, NMR chemical shift perturbations were predominantly localized to residues around the binding pocket of PDZ1, indicating a specific mode of recognition of the cytoplasmic tail of CD63. In addition, the C terminus of syntenin-1 has a stabilizing role in the CD63-syntenin-1 association, as deletion of the last 17 amino acids abolished the interaction. The CD63-syntenin-1 complex is abundant on the plasma membrane, and the elevated expression of the wild-type syntenin-1 slows down constitutive internalization of the tetraspanin. Furthermore, internalization of CD63 was completely blocked in cells expressing a syntenin-1 mutant lacking the first 100 amino acids. Previous results have shown that CD63 is internalized via AP-2-dependent mechanisms. Hence, our data indicate that syntenin-1 can counteract the AP-2-dependent internalization and identify this tandem PDZ protein as a new regulator of endocytosis.
authors.affiliation: CR UK Institute for Cancer Studies, The University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom.
authors.forename: Nadya
authors.initials: N
authors.lastname: Latysheva
authors.forename: Gairat
authors.initials: G
authors.lastname: Muratov
authors.forename: Sundaresan
authors.initials: S
authors.lastname: Rajesh
authors.forename: Matthew
authors.initials: M
authors.lastname: Padgett
authors.forename: Neil A
authors.initials: NA
authors.lastname: Hotchin
authors.forename: Michael
authors.initials: M
authors.lastname: Overduin
authors.forename: Fedor
authors.initials: F
authors.lastname: Berditchevski
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002522:Chlorocebus aethiops; D006224:Cricetinae; D003600:Cytosol / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D010980:Platelet Membrane Glycoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D050827:Syntaxin 1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D060149:Tetraspanin 30
chemical_list: D015703:Antigens, CD; C554586:CD63 protein, human; D010980:Platelet Membrane Glycoproteins; D050827:Syntaxin 1; D060149:Tetraspanin 30