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 an ...
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.
Related Citations:
Improvements in the order, isotropy and electron density of glypican-1 crystals by controlled dehydration. Awad, W.,Svensson Birkedal, G.,Thunnissen, M.M.,Mani, K.,Logan, D.T. (2013) Acta Crystallogr. D Biol. Crystallogr. 69: 2524
Crystal structure of N-glycosylated human glypican-1 core protein: structure of two loops evolutionarily conserved in vertebrate glypican-1. Svensson, G.,Awad, W.,Hakansson, M.,Mani, K.,Logan, D.T. (2012) J. Biol. Chem. 287: 14040
Organizational Affiliation:
the Department of Biochemistry and Cell Biology, University of Gothenburg, Box 440, SE-40530 Gothenburg, and.,the Department of Experimental Medical Science, Lund University, SE-221 84, Lund, Sweden.,From the Department of Biochemistry and Structural Biology, Centre for Molecular Protein Science, Lund University, Box 124, SE-221 00 Lund.,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.
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