Structural Aspects of N-Glycosylations and the C-terminal Region in Human Glypican-1.
Wael AwadBarbara AdamczykJessica ÖrnrosNiclas G KarlssonKatrin ManiDerek T LoganPublished in: The Journal of biological chemistry (2015)
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.
Keyphrases
- cell surface
- crystal structure
- protein protein
- endothelial cells
- high resolution
- amino acid
- signaling pathway
- drug delivery
- binding protein
- magnetic resonance imaging
- transcription factor
- small molecule
- young adults
- epithelial mesenchymal transition
- simultaneous determination
- dual energy
- endoplasmic reticulum stress
- liquid chromatography