Plasminogen activator inhibitor type-1 (PAI-1) has three potential sites for N-linked glycosylation, including Asn209Tyr210Thr211, Asn265Met266Thr267, and Asn329Glu330Ser331. Using a HEK293 expression system, we have made mutants with Asp or Gln substitutions of the Asn residue in each of these sequences. Analyses of these mutants for the content of N-acetyl glucosamine showed that Asn209 and Asn265, but not Asn329, are glycosylated, in agreement with previous suggestions made on the basis of X-ray crystal structure analysis of PAI-1 expressed in CHO cells (Xue et al. (1998) Structure 6, 627-636). In contrast, PAI-1, containing a total of 26 Ser and 26 Thr residues, which are potential targets for O-linked glycosylation, was found to be devoid of N-acetyl-galactosamine, demonstrating the absence of O-linked glycosylation. Analysis of PAI-1 variants with mutational inactivation of each of the sequences utilized for N-linked glycosylation by Fluorophore Assisted Carbohydrate Electrophoresis (FACE), showed a different N-linked glycosylation profile of the glycans at each of the 2 sites. The exact structure of the carbohydrate chains at each of these 2 sequences are being determined using MALDI mass spectrometry and monosaccharide composition analysis and compared to that of natural and recombinant PAI-1 from other sources. These results contribute to a structural basis for previous observations of a different functional importance of the N-linked glycosylation at each of the 2 sequences.
|Publication status||Published - 2002|
|Event||3rd International Symposium on Serpin Biology, Structure and Function - Chicago, IL, USA|
Duration: 1 Jan 2002 → …
|Conference||3rd International Symposium on Serpin Biology, Structure and Function|
|City||Chicago, IL, USA|
|Period||01/01/2002 → …|