Further insight into the roles of the glycans attached to human blood protein C inhibitor

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Wei Sun, Simon Parry, Wimal Ubhayasekera, Åke Engström, Anne Dell, Sophia Schedin-Weiss

Protein C inhibitor (PCI) is a 57-kDa glycoprotein that exists in many tissues and secretions in human. As a member of the serpin superfamily of proteins it displays unusually broad protease specificity. PCI is implicated in the regulation of a wide range of processes, including blood coagulation, fertilization, prevention of tumors and pathogen defence. It has been reported that PCI isolated from human blood plasma is highly heterogeneous, and that this heterogeneity is caused by differences in N-glycan structures, N-glycosylation occupancy, and the presence of two forms that differ by the presence or absence of 6 amino acids at the amino-terminus. In this study we have verified that such heterogeneity exists in PCI purified from single individuals, and that individuals of two different ethnicities possess a similar PCI pattern, verifying that the micro-heterogeneity is conserved among humans. Furthermore, we have provided experimental evidence that PCI in both individuals is O-glycosylated on Thr20 with a core type 1 O-glycan, which is mostly NeuAcGalGalNAc. Modeling suggested that the O-glycan attachment site is located in proximity to several ligand-binding sites of the inhibitor.
Original languageEnglish
JournalBiochemical and Biophysical Research Communications
Volume403
Issue number2
Pages (from-to)198-202
ISSN0006-291X
DOIs
Publication statusPublished - 10 Dec 2010

ID: 33863396