title: Structural Aspects of N-Glycosylations and the C-terminal Region in Human Glypican-1.
abstract: Glypicans are multifunctional cell surface proteoglycans involved in several important cellular signaling pathways. Glypican-1 (Gpc1) is the predominant heparan sulfate proteoglycan in the developing and adult human brain. The two N-linked glycans and the C-terminal domain that attach the core protein to the cell membrane are not resolved in the Gpc1 crystal structure. Therefore, we have studied Gpc1 using crystallography, small angle x-ray scattering, and chromatographic approaches to elucidate the composition, structure, and function of the N-glycans and the C terminus and also the topology of Gpc1 with respect to the membrane. The C terminus is shown to be highly flexible in solution, but it orients the core protein transverse to the membrane, directing a surface evolutionarily conserved in Gpc1 orthologs toward the membrane, where it may interact with signaling molecules and/or membrane receptors on the cell surface, or even the enzymes involved in heparan sulfate substitution in the Golgi apparatus. Furthermore, the N-glycans are shown to extend the protein stability and lifetime by protection against proteolysis and aggregation.
authors.affiliation: From the Department of Biochemistry and Structural Biology, Centre for Molecular Protein Science, Lund University, Box 124, SE-221 00 Lund.
authors.forename: Wael
authors.initials: W
authors.lastname: Awad
authors.affiliation: the Department of Biochemistry and Cell Biology, University of Gothenburg, Box 440, SE-40530 Gothenburg, and.
authors.forename: Barbara
authors.initials: B
authors.lastname: Adamczyk
authors.affiliation: the Department of Biochemistry and Cell Biology, University of Gothenburg, Box 440, SE-40530 Gothenburg, and.
authors.forename: Jessica
authors.initials: J
authors.lastname: Örnros
authors.affiliation: the Department of Biochemistry and Cell Biology, University of Gothenburg, Box 440, SE-40530 Gothenburg, and.
authors.forename: Niclas G
authors.initials: NG
authors.lastname: Karlsson
authors.affiliation: the Department of Experimental Medical Science, Lund University, SE-221 84, Lund, Sweden.
authors.forename: Katrin
authors.initials: K
authors.lastname: Mani
authors.affiliation: From the Department of Biochemistry and Structural Biology, Centre for Molecular Protein Science, Lund University, Box 124, SE-221 00 Lund, derek.logan@biochemistry.lu.se.
authors.forename: Derek T
authors.identifier: http://orcid.org/0000-0002-0098-8560
authors.initials: DT
authors.lastname: Logan
mesh_terms: D000328:Adult; D018360:Crystallography, X-Ray; D006031:Glycosylation; D053673:Glypicans / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D017434:Protein Structure, Tertiary
chemical_list: D053673:Glypicans
keywords: N-linked glycosylation; glypican-1; glypicans; mass spectrometry (MS); membrane-anchored protein; proteoglycan; small angle x-ray scattering (SAXS); structure-function