The defective interaction between von Willebrand factor and factor VIII in a patient with type 1 von Willebrand disease is caused by substitution of Arg19 and His54 in mature von Willebrand factor. Blood 1996 Feb 01;87(3):1013-21
Date
02/01/1996Pubmed ID
8562925DOI
10.1182/blood.v87.3.1013.bloodjournal8731013Scopus ID
2-s2.0-0030040896 (requires institutional sign-in at Scopus site) 54 CitationsAbstract
In this report we describe the further investigation of the von Willebrand factor (vWF)/FVIII interaction in a type 1 von Willebrand disease patient characterized by discrepant VIII:C levels as determined by one-stage and two-stage VIII:C assays. A solid-phase binding assay shows that this patient's plasma vWF is moderately defective in capturing recombinant FVIII. Sequence analysis of the FVIII-binding domain encoded by the vWF mRNA of the affected individual identified mutations in both vWF alleles. In allele A, the mutations C2344T and T2451A result in the substitution of Trp for Arg19 (R19W) and of G1n for His54 (H54Q) in mature vWF, respectively. This allele also contains a reported polymorphism (A2365G, Thr26Ala). Allele B, which is underexpressed at the RNA level, contains a one-nucleotide deletion in the FVIII-binding domain (delta G2515) that results in the premature termination of translation. Analysis of the binding of FVIII by full-length vWF transiently expressed in COS-7 cells confirms that the combined R19W and H54Q substitutions are the cause of the defective vWF/FVIII interaction in this patient. The FVIII-binding defect of vWF containing either mutation alone is approximately half that of the double mutant, which suggests that the effect of these mutations is additive. The mutant proteins are recognized equally well by vWF monoclonal antibodies MBC105.4, 32B12, and 31H3, which block the binding of FVIII by vWF, indicating that amino acids Arg19, Thr26, and His54 are not critical residues in the epitopes of these antibodies.
Author List
Kroner PA, Foster PA, Fahs SA, Montgomery RRAuthor
Robert R. Montgomery MD Adjunct Professor in the Pediatrics department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
AdultAlleles
Animals
Binding Sites
Cell Line, Transformed
DNA Mutational Analysis
Factor VIII
Female
Humans
Mutagenesis, Site-Directed
Point Mutation
Protein Conformation
Recombinant Fusion Proteins
von Willebrand Diseases
von Willebrand Factor
