| 1. |
- Garcia de Frutos, Pablo, et al.
(författare)
-
Differential regulation of alpha and beta chains of C4b-binding protein during acute-phase response resulting in stable plasma levels of free anticoagulant protein S
- 1994
-
Ingår i: Blood. - 1528-0020. ; 84:3, s. 815-822
-
Tidskriftsartikel (refereegranskat)abstract
- Regulation of C4b-binding protein (C4BP) isoforms during acute phase and its relationship to the plasma concentration of free protein S was elucidated. An assay for beta chain containing C4BP (C4BP beta+) was developed and the concentrations of total C4BP, C4BP beta+, total, free, and bound protein S were measured in patients with acute-phase response. Even though total C4BP was increased to 162% (mean value) of controls, the corresponding value of C4BP beta+ was only 122%. In the acute-phase group, total protein S was increased to the same extent as C4BP beta+ (mean value of 124%), whereas free protein S was not decreased. In controls, total and bound protein S correlated with total C4BP and C4BP beta+. However, in the acute-phase group, the correlation between bound protein S and total C4BP was lost, although the correlation between C4BP beta+ and protein S remained. The present results suggest stable levels of free protein S during acute phase to be the result of differential regulation of C4BP alpha- and beta-chain expression, and the concentration of free protein S to be the resulting molar excess of protein S over C4BP beta+. This mechanism ensures functional levels of free anticoagulant protein S despite high levels of C4BP.
|
|
| 2. |
- Garcia de Frutos, Pablo, et al.
(författare)
-
Differential regulation of α and β chains of C4b-binding protein during acute-phase response resulting in stable plasma levels of free anticoagulant protein S
- 1994
-
Ingår i: Blood. - 1528-0020. ; 84:3, s. 815-822
-
Tidskriftsartikel (refereegranskat)abstract
- Regulation of C4b-binding protein (C4BP) isoforms during acute phase and its relationship to the plasma concentration of free protein S was elucidated. An assay for β chain containing C4BP (C4BPβ+) was developed and the concentrations of total C4BP, C4BPβ+, total, free, and bound protein S were measured in patients with acute-phase response. Even though total C4BP was increased to 162% (mean value) of controls, the corresponding value of C4BPβ+ was only 122%. In the acute-phase group, total protein S was increased to the same extent as C4BPβ+ (mean value of 124%), whereas free protein S was not decreased. In controls, total and bound protein S correlated with total C4BP and C4BPβ+. However, in the acute-phase group, the correlation between bound protein S and total C4BP was lost, although the correlation between C4BPβ+ and protein S remained. The present results suggest stable levels of free protein S during acute phase to be the result of differential regulation of C4BP α- and β-chain expression, and the concentration of free protein S to be the resulting molar excess of protein S over C4BPβ+. This mechanism ensures functional levels of free anticoagulant protein S despite high levels of C4BP.
|
|
| 3. |
- Hillarp, Andreas, et al.
(författare)
-
Bovine C4b binding protein. Molecular cloning of the alpha- and beta-chains provides structural background for lack of complex formation with protein S
- 1994
-
Ingår i: Journal of immunology. - 0022-1767. ; 153:9, s. 4190-4199
-
Tidskriftsartikel (refereegranskat)abstract
- C4b binding protein (C4BP) regulates the complement system. It also interacts with anticoagulant protein S and with serum amyloid P component. Human C4BP is composed of seven identical 70-kDa alpha-chains and one 45-kDa beta-chain. The binding site for C4b is located on the alpha-chain, whereas the beta-chain binds protein S. Nothing is known about the structure and function of bovine C4BP. No complexed form of protein S was detected by using a gel filtration chromatography system combined with Western blotting. Bovine cDNA clones encoding the C4BP alpha- and beta-chains were isolated from a bovine liver cDNA library. Three overlapping alpha-chain clones predicted a 562-amino acid residues-long mature polypeptide. The overall amino acid sequence similarity with the human alpha-chain was 61%. Like its human counterpart, the bovine alpha-chain is composed of eight contiguous short consensus repeat units, each of approximately 60 amino acid residues, and a carboxyl-terminal nonrepeat region. One bovine beta-chain clone was found and characterized. It predicted a mature bovine beta-chain of 181 amino acid residues. The identity with the human beta-chain was 65% at the amino acid level. A noteworthy difference between bovine and human beta-chains was that the bovine beta-chain only contained two short consensus repeats compared with three in human beta-chain. Sequence alignment indicates that the region corresponding to residues 1-60 (repeat 1) in the human beta-chain is absent in the homologous bovine polypeptide. Because the short consensus repeats of the human beta-chain contain the binding site for protein S, the lack of one repeat unit in the bovine beta-chain may provide a clue to the lack of complex formation between C4BP and protein S in bovine plasma.
|
|
| 4. |
- Hillarp, Andreas, et al.
(författare)
-
Cloning of cDNA coding for the beta chain of human complement component C4b-binding protein : sequence homology with the alpha chain
- 1990
-
Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424. ; 87:3, s. 1183-1187
-
Tidskriftsartikel (refereegranskat)abstract
- The major form of complement component C4b-binding protein, a regulator of the complement system, is composed of seven identical 70-kDa alpha chains, each containing a binding site for the complement protein C4b. We recently showed that C4b-binding protein also contains a unique 45-kDa beta chain. It is disulfide-linked to the central core and contains a binding site for the vitamin K-dependent protein S. We have now isolated and characterized full-length cDNA clones for the beta chain. In addition, 57% of the structure was determined by protein sequencing of tryptic and chymotryptic peptides. Two clones, A8 and C1, isolated from different libraries were sequenced. Except for a deleted triplet encoding Ala-3 in clone A8, the two clones were identical and coded for a leader sequence of 17 amino acids and a mature protein of 235 amino acids (including Ala-3). By N-terminal amino acid sequencing, the Ala-3 heterogeneity was confirmed and a third beta-chain species starting at Glu-4 was identified. The beta chain contains five potential N-linked glycosylation sites, and endoglycosidase digestion suggested that the beta chain contained multiple complex carbohydrate side chains. Northern blot analysis of human liver mRNA, using the beta-chain cDNA as the probe, demonstrated a major mRNA species of approximately 1.0 kilobase. From the N terminus, the beta chain contains three tandem repeat units (60 amino acids long) that are homologous to those present in the alpha chain. The C-terminal region, which was unrelated to the tandem repeats, demonstrated sequence similarity with the corresponding region of the alpha chain. In both alpha and beta chains these regions contain two cysteine residues that probably form the interchain disulfide bridges.
|
|
| 5. |
|
|
| 6. |
- Schwalbe, Ruth, et al.
(författare)
-
Assembly of protein S and C4b-binding protein on membranes
- 1990
-
Ingår i: The Journal of biological chemistry. - 0021-9258. ; 265:27, s. 16074-16081
-
Tidskriftsartikel (refereegranskat)abstract
- The interaction of protein S with membranes and subsequent combination with complement C4b-binding protein (C4BP) was studied. Protein S interacted with phospholipid vesicles in a calcium-dependent manner typical of other vitamin K-dependent proteins. Association of C4BP with protein S showed no apparent selectivity for membrane-bound or solution phase protein S. When bound to the membrane, the protein complexes projected out from the vesicle surface and induced vesicle radius changes of 11.4 nm for tightly packed protein S alone and 17.5 nm for the protein S-C4BP complex. Due to a low density of the protein S-C4BP on the membrane at saturation, the actual projection of this complex out from the membrane surface would be much greater than 17.5 nm. A low saturation density suggested that the protein complex had a large two-dimensional hydrodynamic radius in the plane of the membrane that prevented tight packing of protein. In the presence of calcium, the protein-protein interaction was rapid (ka greater than or equal to 1.10(6) M-1 s-1) and had very high affinity (KD less than or equal to 10(-10) M). The dissociation rate was slow with an estimated rate constant of less than or equal to 2.10(-4) s-1 at 25 degrees C. Protein-protein interaction was much slower in the absence of calcium with an estimated association rate constant of only 2.10(4) M-1 s-1. Consequently, the protein-protein interaction was greatly enhanced by calcium. The very high affinity interaction between protein S and C4BP suggested specificity and an important function for the protein S-C4BP complex in blood. In this regard it was important that C4BP which was bound to protein S on the phospholipid surface could interact with complement protein C4b. These results suggested that protein S may serve an important role in localizing C4BP to negatively charged phospholipid. This would provide regulation of complement activation at sites where the coagulation system is activated such as on the surface of activated platelets.
|
|
| 7. |
- Zöller, Bengt, et al.
(författare)
-
Identification of the same factor V gene mutation in 47 out of 50 thrombosis-prone families with inherited resistance to activated protein C
- 1994
-
Ingår i: Journal of Clinical Investigation. - 0021-9738. ; 94:6, s. 2521-2524
-
Tidskriftsartikel (refereegranskat)abstract
- Resistance to activated protein C (APC) is the most prevalent inherited cause of venous thrombosis. The APC resistance phenotype is associated with a single point mutation in the factor V gene, changing Arg506 in the APC cleavage site to a Gln. We have investigated 50 Swedish families with inherited APC resistance for this mutation and found it to be present in 47 of them. Perfect cosegregation between a low APC ratio and the presence of mutation was seen in 40 families. In seven families, the co-segregation was not perfect as 12 out of 57 APC-resistant family members were found to lack the mutation. Moreover, in three families with APC resistance, the factor V gene mutation was not found, suggesting another still unidentified cause of inherited APC resistance. Of 308 investigated families members, 146 were normal, 144 heterozygotes, and 18 homozygotes for the factor V gene mutation and there were significant differences in thrombosis-free survival curves between these groups. By age 33 yr, 8% of normals, 20% of heterozygotes, and 40% of homozygotes had had manifestation of venous thrombosis.
|
|
| 8. |
- Zöller, Bengt, et al.
(författare)
-
Linkage between inherited resistance to activated protein C and factor V gene mutation in venous thrombosis
- 1994
-
Ingår i: The Lancet. - 1474-547X. ; 343:8912, s. 1536-1538
-
Tidskriftsartikel (refereegranskat)abstract
- Resistance to activated protein C (APC) is a major cause of familial thrombophilia, and can be corrected by an anticoagulant activity expressed by purified factor V. We investigated linkage between APC resistance and the factor V gene in a large kindred with familial thrombophilia. Restriction fragment length polymorphisms in exon 13 of the factor V gene were informative in 14 family members. The 100% linkage between factor V gene polymorphism and APC resistance strongly suggested a factor V gene mutation as a cause of APC resistance. A point mutation changing Arg506 in the APC cleavage site to a Gln was found in APC resistant individuals. These results suggest factor V gene mutation to be the most common genetic cause of thrombophilia.
|
|
