title: Identification of novel sphingolipid-binding motifs in mammalian membrane proteins.
abstract: Specific interactions between transmembrane proteins and sphingolipids is a poorly understood phenomenon, and only a couple of instances have been identified. The best characterized example is the sphingolipid-binding motif VXXTLXXIY found in the transmembrane helix of the vesicular transport protein p24. Here, we have used a simple motif-probability algorithm (MOPRO) to identify proteins that contain putative sphingolipid-binding motifs in a dataset comprising proteomes from mammalian organisms. From these motif-containing candidate proteins, four with different numbers of transmembrane helices were selected for experimental study: i) major histocompatibility complex II Q alpha chain subtype (DQA1), ii) GPI-attachment protein 1 (GAA1), iii) tetraspanin-7 TSN7, and iv), metabotropic glutamate receptor 2 (GRM2). These candidates were subjected to photo-affinity labeling using radiolabeled sphingolipids, confirming all four candidate proteins as sphingolipid-binding proteins. The sphingolipid-binding motifs are enriched in the 7TM family of G-protein coupled receptors, predominantly in transmembrane helix 6. The ability of the motif-containing candidate proteins to bind sphingolipids with high specificity opens new perspectives on their respective regulation and function.
authors.affiliation: Center for Biomembrane Research, Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden; Science for Life Laboratory, Stockholm University, SE-171 21 Solna, Sweden.
authors.forename: Patrik
authors.initials: P
authors.lastname: Björkholm
authors.affiliation: Heidelberg University Biochemistry Center, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany.
authors.forename: Andreas M
authors.initials: AM
authors.lastname: Ernst
authors.affiliation: Heidelberg University Biochemistry Center, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany.
authors.forename: Moritz
authors.initials: M
authors.lastname: Hacke
authors.affiliation: Heidelberg University Biochemistry Center, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany.
authors.forename: Felix
authors.initials: F
authors.lastname: Wieland
authors.affiliation: Heidelberg University Biochemistry Center, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany.
authors.forename: Britta
authors.initials: B
authors.lastname: Brügger
authors.affiliation: Center for Biomembrane Research, Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden; Science for Life Laboratory, Stockholm University, SE-171 21 Solna, Sweden.
authors.forename: Gunnar
authors.initials: G
authors.lastname: von Heijne
mesh_terms: D020816:Amino Acid Motifs; D037263:Asialoglycoprotein Receptor / Q000378:metabolism; D015153:Blotting, Western; D002462:Cell Membrane / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D008562:Membrane Glycoproteins / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism; D010446:Peptide Fragments / Q000378:metabolism*; D013107:Sphingolipids / Q000378:metabolism*; D059470:Tetraspanins / Q000378:metabolism
chemical_list: C546927:ASGR1 protein, human; D037263:Asialoglycoprotein Receptor; C093316:GPAA1 protein, human; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D010446:Peptide Fragments; D013107:Sphingolipids; C404405:TSPAN7 protein, human; D059470:Tetraspanins
keywords: Membrane protein; Sphingolipid; Transmembrane helix