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Disulfide bonds required to assemble functional von Willebrand factor multimers
The hemostatic functions of human von Willebrand Factor (vWF) depend on the normal assembly of disulfide-linked multimers from approximately 250-kDa subunits. Subunits initially form dimers through disulfide bonds near the COOH terminus. Dimers then form multimers through disulfide bonds near the NH...
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Published in: | The Journal of biological chemistry 1994-03, Vol.269 (9), p.6753-6758 |
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Main Authors: | , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | The hemostatic functions of human von Willebrand Factor (vWF) depend on the normal assembly of disulfide-linked multimers
from approximately 250-kDa subunits. Subunits initially form dimers through disulfide bonds near the COOH terminus. Dimers
then form multimers through disulfide bonds near the NH2 terminus of each subunit. Previous studies of plasma vWF and recombinant
vWF fragments indicate that 1 or more of the Cys residues at position 459, 462, and 464 form intersubunit disulfide bonds.
No evidence has been reported that vWF multimer formation involves additional intersubunit bonds. To probe the disulfide bond
requirements for multimer formation, mutant vWF proteins were expressed in which all 3 Cys residues at positions 459, 462,
and 464 were changed to either Gly or Ala. Surprisingly, none of these cysteines appears to be necessary for efficient multimer
assembly. Furthermore, recombinant vWF with Gly or Ala at all three positions induces platelet aggregation in the presence
of ristocetin and binds to platelet glycoprotein Ib, factor VIII, and collagen in a manner similar to wild-type recombinant
vWF. These results suggest that other intersubunit disulfide bonds must exist. Direct evidence for such a bond was obtained
by characterization of tryptic fragments of vWF. By Edman degradation, amino acid composition, and mass spectrometry, a disulfide
bond was demonstrated between Cys379 residues of adjacent vWF subunits. Thus, intersubunit disulfide bonds involving Cys379
and 1 or more of the Cys residues at positions 459, 462, and 464 connect the NH2-terminal ends of the vWF subunits in a parallel
orientation. |
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ISSN: | 0021-9258 1083-351X |
DOI: | 10.1016/S0021-9258(17)37439-2 |