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The O-glycomap of L...
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Ali, LiaqatGothenburg University,Göteborgs universitet,Institutionen för biomedicin, avdelningen för medicinsk kemi och cellbiologi,Institute of Biomedicine, Department of Medical Biochemistry and Cell Biology
(author)
The O-glycomap of Lubricin, a Novel Mucin Responsible for Joint Lubrication, Identified by Site-specific Glycopeptide Analysis
- Article/chapterEnglish2014
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LIBRIS-ID:oai:gup.ub.gu.se/210495
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https://gup.ub.gu.se/publication/210495URI
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https://doi.org/10.1074/mcp.M114.040865DOI
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Subject category:ref swepub-contenttype
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Subject category:art swepub-publicationtype
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The lubricative, heavily glycosylated mucin-like synovial glycoprotein lubricin has previously been observed to contain glycosylation changes related to rheumatoid and osteoarthritis. Thus, a site-specific investigation of the glycosylation of lubricin was undertaken, in order to further understand the pathological mechanisms involved in these diseases. Lubricin contains an serine/threonine/proline (STP)-rich domain composed of imperfect tandem repeats (EPAPTTPK), the target for O-glycosylation. In this study, using a liquid chromatography-tandem mass spectrometry approach, employing both collision-induced and electron-transfer dissociation fragmentation methods, we identified 185 O-glycopeptides within the STP-rich domain of human synovial lubricin. This showed that adjacent threonine residues within the central STP-rich region could be simultaneously and/or individually glycosylated. In addition to core 1 structures responsible for biolubrication, core 2 O-glycopeptides were also identified, indicating that lubricin glycosylation may have other roles. Investigation of the expression of polypeptide N-acetylgalactosaminyltransferase genes was carried out using cultured primary fibroblast-like synoviocytes, a cell type that expresses lubricin in vivo. This analysis showed high mRNA expression levels of the less understood polypeptide N-acetylgalactosaminyltransferase 15 and 5 in addition to the ubiquitously expressed polypeptide N-acetylgalactosaminyltransferase 1 and 2 genes. This suggests that there is a unique combination of transferase genes important for the O-glycosylation of lubricin. The site-specific glycopeptide analysis covered 82% of the protein sequence and showed that lubricin glycosylation displays both micro-and macroheterogeneity. The density of glycosylation was shown to be high: 168 sites of O-glycosylation, predominately sialylated, were identified. These glycosylation sites were focused in the central STP-rich region, giving the domain a negative charge. The more positively charged lysine and arginine residues in the N and C termini suggest that synovial lubricin exists as an amphoteric molecule. The identification of these unique properties of lubricin may provide insight into the important low-friction lubricating functions of lubricin during natural joint movement.
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Flowers, Sarah A.Gothenburg University,Göteborgs universitet,Institutionen för biomedicin, avdelningen för medicinsk kemi och cellbiologi,Institute of Biomedicine, Department of Medical Biochemistry and Cell Biology
(author)
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Jin, ChunshengGothenburg University,Göteborgs universitet,Institutionen för biomedicin, avdelningen för medicinsk kemi och cellbiologi,Institute of Biomedicine, Department of Medical Biochemistry and Cell Biology(Swepub:gu)xjinch
(author)
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Bennet, E. P.
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Ekwall, Anna-Karin HGothenburg University,Göteborgs universitet,Institutionen för medicin, avdelningen för reumatologi och inflammationsforskning,Institute of Medicine, Department of Rheumatology and Inflammation Research(Swepub:gu)xhannp
(author)
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Karlsson, Niclas G.,1966Gothenburg University,Göteborgs universitet,Institutionen för biomedicin, avdelningen för medicinsk kemi och cellbiologi,Institute of Biomedicine, Department of Medical Biochemistry and Cell Biology(Swepub:gu)xkanic
(author)
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Göteborgs universitetInstitutionen för biomedicin, avdelningen för medicinsk kemi och cellbiologi
(creator_code:org_t)
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In:Molecular & Cellular Proteomics13:12, s. 3396-34091535-9476
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