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

• 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 N-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 microheterogeneity is conserved among humans. Furthermore, we have provided experimental evidence that PCI is O-glycosylated on Thr20 with the O-glycan structure composition NeuAcGalGalNAc. This glycan was conserved in the two individuals and did not contribute to the size heterogeneity. Modeling suggested that the O-glycan attachment site is located in proximity to several ligand-binding sites of the inhibitor.  

Subject headings

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinsk bioteknologi -- Medicinsk bioteknologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Medical Biotechnology -- Medical Biotechnology (hsv//eng)

NATURVETENSKAP  -- Biologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences (hsv//eng)

Keyword

Microheterogeneity

Mass spectrometry

O-glycosylation

Protein C inhibitor

Serpin

Biochemistry

Biokemi

Biokemi

Biochemistry

Micro-heterogeneity

Mass spectrometry

O-glycosylation

Protein C

inhibitor

Serpin

Publication and Content Type

ref (subject category)

art (subject category)