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A monoclonal antibody recognizing the activation domain of protein C in its calcium‐free conformation
Author(s) -
Vincenot Anne,
Pittet Jean-Louis,
Aiach Martine,
Gaussem Pascale
Publication year - 1998
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(98)00802-3
Subject(s) - monoclonal antibody , calcium , chemistry , antibody , calcium binding protein , domain (mathematical analysis) , biophysics , biochemistry , biology , immunology , mathematics , organic chemistry , mathematical analysis
A monoclonal antibody (mAb) binding to protein C (PC) heavy chain but not to activated PC was found to inhibit PC activation by free thrombin, suggesting that epitope involved the activation site. Using a set of overlapping synthetic peptides, we confirmed that this mAb recognizes the sequence encompassing the thrombin cleavage site ( 165 QVDPRLI 171 ). Surprisingly, epitope was only accessible in the absence of calcium, half‐maximal inhibition of mAb binding occurring at 100 μM Ca 2+ . Thus, our antibody provides direct evidence that conformation and/or accessibility of the activation site differ between the apo and Ca 2+ ‐stabilized conformers of PC.