Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.16.3.1 (ceruloplasmin)
 5,074 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mutations leading to hemophilia A by substitution of amino acids in coagulation factor VIII may provide important clues to the structure and function of this large and enigmatic protein. To efficiently find missense mutations, hemophiliacs with mild and moderately severe forms of the disease were surveyed. DNA samples from affected individuals were assayed for mutations by denaturing gradient gel electrophoresis following DNA amplification of target regions, which included all coding regions except for that of the dispensable B domain. Missense mutations were observed in 20 of the 34 patients examined, with identical mutations found in five pairs of patients. All mutations were found in the repetitive A and C domains. By aligning these domains in factor VIII with homologous domains in factor V, ceruloplasmin, and the mouse milk fat globule membrane protein, it was determined that most mutations change amino acids in areas of strong sequence conservation. Three additional mutations were detected, including a point mutation in an intron, a stop codon mutation, and a silent base change. Ten of the 18 different mutations discovered in this patient population are reported here for the first time.
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PMID:Amino acid substitutions in conserved domains of factor VIII and related proteins: study of patients with mild and moderately severe hemophilia A. 130 32

The hemophilia A mutation database lists more than 160 missense mutations: each represents a molecular defect in the FVIII molecule, resulting in the X-linked bleeding disorder hemophilia A with a clinical presentation varying from mild to severe. Without a three-dimensional FVIII structure it is in most cases impossible to explain biological dysfunction in terms of the underlying molecular pathology. However, recently the crystal structure of the homologous human plasma copper-binding protein ceruloplasmin (hCp) has been solved, and the A domains of FVIII share approximately 34% sequence identity with hCp. This advance has enabled the building of a molecular model of the A domains of FVIII based on the sequence identity between the two proteins. The model allows exploration of predictions regarding the general features of the FVIII molecule, such as the binding-sites for factor IXa and activated protein C; it has also allowed the mapping of more than 30 selected mutations with known phenotype from the database, and the prediction of hypothetical links to dysfunction in all but a few cases. A computer-generated molecular model such as that reported here cannot substitute for a crystal structure. However, until such a structure for FVIII becomes available, the model represents a significant advance in modeling FVIII; it should prove a useful tool for exploiting the increasing amount of information in the hemophilia A mutation database, and for selecting appropriate targets for investigation of the structure-function relationships via mutagenesis and expression in vitro.
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PMID:A molecular model for the triplicated A domains of human factor VIII based on the crystal structure of human ceruloplasmin. 911 85

A 42-year-old patient with mild hemophilia A developed spontaneous muscle hematomas 1 month after intense therapy with factor VIII concentrates. Factor VIII clotting activity was less than 1% and his factor VIII inhibitor was 10 Bethesda units (BU)/mL. The titer peaked at 128 BU despite daily infusions of factor VIII; 1 year later, the titer was 13 BU with no spontaneous bleeding for 4 months. The plasma inhibitor was 95% neutralized by factor VIII A2 domain but less than 15% neutralized by light-chain or C2 domain. His inhibitor did not cross-react with porcine factor VIII and was at least 10-fold less reactive to a series of hybrid factor VIII proteins in which human residues 484-508 are replaced by the homologous porcine sequence (Healey et al, J Biol Chem 270:14505, 1995). The inhibitor patient's DNA encoding his A2 domain and flanking sequences showed a C-T transition predicting Arg593 to Cys. Thirteen patients from 5 unrelated families with Cys593 have not developed inhibitors. Factor VIII clotting activity from one of them was inhibited similarly to diluted normal plasma by inhibitor patient plasma. In an homologous structure, ceruloplasmin (Zaitseva et al, J Biol Inorgan Chem 1:15, 1996), the residue equivalent to Arg593, is in a loop distinct from residues 484-508. On solution phase immunoprecipitation with labeled factor VIII fragments, A2, light chain, and C2 domains bound. In contrast to typical immune responses to factor VIII in patients with severe hemophilia A, this patient's inhibitor was almost entirely reactive with common epitopes within the A2 domain whereas by more sensitive immunoprecipitation testing antibodies to light chain epitopes were also present. Accordingly, immune responsiveness to exogenous factor VIII (antigen burden) appears to be more critical than his endogenous, hemophilic factor VIII to his developing high-titer anti-factor VIII antibodies and loss of tolerance to both native and hemophilic factor VIII proteins.
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PMID:Loss of tolerance to exogenous and endogenous factor VIII in a mild hemophilia A patient with an Arg593 to Cys mutation. 929 23

Factor (F) VIII is a large gene located near the terminus of the long arm of the X chromosome. It contains 26 exons that code for a signal peptide and a 2332 amino acid polypeptide with three different types of domains, namely A1-A2-B-A3-C1-C2. The A domains are homologous with each other and those of ceruloplasmin; substitution into the known crystal structure of the copper binding protein produces molecular models. The large, central B domain is highly glycosylated but has a variable sequence, even among FVIIIs from different species. Most of B can be deleted and the resulting recombinant protein has essentially normal survival in circulation and corrects the bleeding tendency in hemophilia A patients. The C domains are similar to each other, and the crystal structure of a recombinant human C2 domain is known, allowing construction of a molecular model of C1. The FVIII protein is secreted as a heterodimer following at least two intracellular cleavages within the B domain. In circulation it is stabilized by binding to von Willebrand factor (vWF) with a plasma half-life of about 10 hours. After specific thrombin cleavages that remove the remainder of the B domain and one of the high-affinity von Willebrand factor binding sites, FVIII becomes heterotrimeric FVIIIa, capable of enhancing intrinsic FX activation by FIXa. Inactivation of FVIIIa occurs by A2 dissociation or by specific cleavages within A1 and A2 by activated protein C. Control of intrinsic FX activation is critical for hemostasis and thrombosis.
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PMID:Structure and function of the factor VIII gene and protein. 1264 May 60