Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P02749 (beta2-glycoprotein I)
 836 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The synthesis of various products by a human mammary cell line (BT 20) was studied by incorporation of 14C-labeled amino acids, choline, glucosamine, or galactosamine into nondialyzable materials. These products had molecular weights ranging from less than 12,300 daltons to more than 200,000 daltons. They were analyzed by immunoelectrophoresis and double diffusion in agar. Among the synthesized products, the following proteins were identified: beta2-glycoprotein I, alpha2HS-glycoprotein, alpha2-lipoprotein, actin, beta2-microglobulin, carcinoembryonic antigen, three oncofetal-associated antigens, and various erythrocyte membrane-associated antigens (namely, glycophorin). Synthesis of milk proteins was not detectable. Only the protein moiety of the glycophorin molecule seemed to be synthesized. The beta2-microglobulin was synthesized in an unbound state as well as bound to a glycoprotein whose relationship with the transplantation or tumor antigens must be determined. The three oncofetal-associated antigens were also synthesized in vitro by human fetal tissues and neoplastic and dysplastic human mammary tissues.
J Natl Cancer Inst 1978 Sep
PMID:Antigens of a human breast carcinoma cell line (BT 20). I. Synthesis of serum proteins, membrane-associated antigens, and oncofetal-associated antigens. 35 46

The serum level of beta2-glycoprotein I has been measured in a sample of 532 healthy, unrelated Caucasians resident in Melbourne. The distribution of levels is bimodal but lacks complete separation of the two modes. Samples with levels below 14.0 mg/100 ml are considered to be type I, and those above this level to be type N. The present sample contains 42 subjects of the former phenotype and 490 of the latter. The phenotypes are distributed equally between males and females and between smokers and nonsmokers and are unrelated to age, birth rank, or parental age. The gene frequencies for the Melbourne sample are compared with those found in various European samples. The beta2-glycoprotein I level of type N males is higher than that of females, and smokers have a higher level than nonsmokers. The positive regression of level on age is significant when corrections are made for sex and smoking status. beta2-glycoprotein I level is highly correlated with pseudocholinesterase activity. The pattern of inheritance of phenotypes has been examined in 17 families with a total of 56 children. In all families, this pattern is consistent with the currently accepted mode of autosomal codominant transmission.
Hum Genet 1978 Sep 19
PMID:The relation of sex, smoking status, birth rank, and parental age to beta2-glycoprotein I levels and phenotypes in a sample of Australian Caucasian adults. 70 Jul 2

IgG was isolated from 9 patients with high levels of anticardiolipin antibodies (aCL). The standard ELISA was modified, using gelatin to postcoat ELISA plates and as diluent. Under these conditions, 8/9 samples of IgG bound to cardiolipin only in the presence of a cofactor, found in fetal calf serum and normal human serum (NHS). beta 2-glycoprotein I (apolipoprotein H) was at least as effective as NHS as a cofactor for 7/9 IgG samples. Our studies confirm that for some aCL detected in conventional assays, the antibody will react with cardiolipin only if beta 2-glycoprotein I is present.
J Rheumatol 1992 Sep
PMID:Antiphospholipid antibodies require beta 2-glycoprotein I (apolipoprotein H) as cofactor. 143 8

Plasmas of 16 patients positive for both IgG anticardiolipin (aCL) antibodies and lupus anticoagulant (LA) antibodies were subjected to adsorption with liposomes containing cardiolipin. In 5 of these plasmas both the anticardiolipin and the anticoagulant activities were co-sedimented with the liposomes in a dose-dependent manner, whereas in the remaining cases only the anticardiolipin activity could be removed by the liposomes, leaving the anticoagulant activity (LA) in the supernatant plasma. aCL antibodies purified from the first 5 plasmas were defined as aCL-type A, while the term aCL-type B was used for antibodies in the other 11 plasmas, from which 2 were selected for this study. Prolongation of the dRVVT was produced by affinity-purified aCL-type A antibodies in plasma of human as well as animal (bovine, rat and goat) origin. aCL-type B antibodies were found to be devoid of anticoagulant activity, while the corresponding supernatants containing LA IgG produced prolongation of the dRVVT only in human plasma. These anticoagulant activities of aCL-type A and of LA IgG's were subsequently evaluated in human plasma depleted of beta 2-glycoprotein I (beta 2-GPI), a protein which was previously shown to be essential in the binding of aCL antibodies to anionic phospholipids. Prolongation of the dRVVT by aCL-type A antibodies was abolished using beta 2-GPI deficient plasma, but could be restored upon addition of beta 2-GPI. In contrast, LA IgG caused prolongation of the dRVVT irrespective of the presence or absence of beta 2-GPI.(ABSTRACT TRUNCATED AT 250 WORDS)
Thromb Haemost 1992 Sep 07
PMID:Anticoagulant activity of beta 2-glycoprotein I is potentiated by a distinct subgroup of anticardiolipin antibodies. 144 Apr 95

It has been reported that antiphospholipid autoantibodies do not recognize phospholipid alone, but rather the plasma protein beta 2-glycoprotein I (beta 2GPI), or a beta 2GPI-phospholipid complex. In vitro beta 2GPI binds to anionic phospholipids and inhibits the prothrombinase activity of procoagulant membranes. In light of the fact that lupus anticoagulants, a type of antiphospholipid antibody, have similar anticoagulant properties, the relationship of beta 2GPI to lupus anticoagulant activity was investigated. IgG from patients with autoimmune diseases or syphilis were tested for anticardiolipin reactivity and lupus anticoagulant activity in the presence and absence of beta 2GPI. As expected, anti-cardiolipin reactivity associated with autoimmune disease was beta 2GPI dependent. In contrast, IgG from a patient with syphilis recognized cardiolipin alone and binding was inhibited by beta 2GPI. Autoimmune antiphospholipid antibodies prolonged the dilute Russell viper venom time of normal plasma, but had no effect on beta 2GPI-depleted plasma. Antiphospholipid antibodies associated with syphilis had no anticoagulant effect. RP-1, an anti-beta 2GPI mAb, had anticoagulant effects similar to those of autoimmune antiphospholipid antibodies. These data demonstrate that antiphospholipid autoantibodies exert lupus anticoagulant activity via an interaction with beta 2GPI. These antibodies and RP-1 appear to amplify the anticoagulant effect of beta 2GPI itself.
J Clin Invest 1992 Sep
PMID:Lupus anticoagulant activity of autoimmune antiphospholipid antibodies is dependent upon beta 2-glycoprotein I. 152 18

A subset of patients with systemic lupus erythematosus has autoantibodies to acidic phospholipids. Since lipids are poor immunogens, the mechanism responsible for the induction of these antibodies is unclear. Immunization of a normal rabbit and normal mice with purified human beta 2-glycoprotein I (apolipoprotein H) resulted in the production of high levels of two non-cross-reactive antibody populations, anti-apolipoprotein H, and antiphospholipid. The antiphospholipid antibodies had binding specificities indistinguishable from autoantibodies obtained from human and murine lupus. These findings suggest a novel mechanism for the induction of antiphospholipid autoantibodies.
J Clin Invest 1992 Sep
PMID:Induction of antiphospholipid autoantibodies by immunization with beta 2 glycoprotein I (apolipoprotein H). 152 19

Inactivation of activated protein C (APC) in normal human plasma was studied in the absence and presence of heparin. In the absence of heparin APC inactivation followed pseudo-first order kinetics. In the presence of heparin the neutralization of APC was found to be biphasic. Up to 500 nM APC could be readily inactivated in normal plasma, indicating that the concentration of the APC inhibitor must be higher than previously assumed. Plasma deficient in the protein C inhibitor (PCI-I, as described by Suzuki and coworkers) and deficient in beta 2-glycoprotein I still possessed APC neutralizing capacity, presumably through the formation of complexes of APC with another plasma protein as was demonstrated by immunoblotting with anti-protein C antibodies. Together these data made us to conclude that a second inhibitor of APC (PCI-II) must be present in normal human plasma. This second inhibitor should be heparin independent, have a relatively high plasma concentration and form complexes with APC. Subsequently, we purified this PCI-II by isolating APC-PCI-II complexes from plasma deficient of vitamin K dependent proteins, PCI-I and beta 2-glycoprotein-I, to which purified human APC had been added. Purified PCI-II has a molecular weight of 50,000 daltons and aminoacid analysis revealed that PCI-II is identical with alpha 1-antitrypsin (alpha 1-AT). The second order rate constant for the reaction between purified alpha 1-AT and APC was found to be 269 M-1 min-1 in the absence of calcium and 602 M-1 min-1 in the presence of calcium.(ABSTRACT TRUNCATED AT 250 WORDS)
Thromb Haemost 1989 Sep 29
PMID:A second plasma inhibitor of activated protein C: alpha 1-antitrypsin. 255 21

The horseshoe crab clotting factor, factor C, present in the hemocytes is a serine-protease zymogen activated with lipopolysaccharide. It is a two-chain glycoprotein (Mr = 123,000) composed of a heavy chain (Mr = 80,000) and a light chain (Mr = 43,000) [T. Nakamura et al. (1986) Eur. J. Biochem. 154, 511-521]. In our continued study of this zymogen, we have now also found a single-chain form of factor C (Mr = 123,000) in the hemocyte lysate. The heavy chain had the NH2-terminal sequence of Ser-Gly-Val-Asp-, consistent with that of the single-chain factor C, indicating that the heavy chain is derived from the NH2-terminal part of the molecule. The light chain had an NH2-terminal sequence of Ser-Ser-Gln-Pro-. Incubation of the two-chain zymogen with lipopolysaccharide resulted in the cleavage of a Phe-Ile bond between residues 72 and 73 of the light chain. Concomitant with this cleavage, the A (72 amino acid residues) and B chains derived from the light chain were formed. The complete amino acid sequence of the A chain was determined by automated Edman degradation. The A chain contained a typical segment which is similar in sequence to a family of repeats in human beta 2-glycoprotein I, complement factors B, protein H, C4b-binding protein, and coagulation factor XIII b subunit. The NH2-terminal sequence of the B chain was Ile-Trp-Asn-Gly-. This chain contained the serine-active site sequence-Asp-Ala-Cys-Ser-Gly-Asp-Ser-Gly-Gly-Pro-. These results indicate that horseshoe crab factor C exists in the hemocytes in a single-chain zymogen form and is converted to an active serine protease by hydrolysis of a specific Phe-Ile peptide bond.
Eur J Biochem 1987 Sep 15
PMID:Lipopolysaccharide-sensitive serine-protease zymogen (factor C) of horseshoe crab hemocytes. Identification and alignment of proteolytic fragments produced during the activation show that it is a novel type of serine protease. 330 57

An 18-year-old woman with primary antiphospholipid syndrome developed a major cerebral infarction leading to brain death despite intensive treatment with steroids, urokinase, glyceol and heparin. Fatal strokes associated with this syndrome are rare. A computed tomographic scan of the brain suggested occlusion of the main trunk of the right middle cerebral artery. The titer of antibodies against cardiolipin/ beta 2-glycoprotein I complex in serum was extremely high.
Jpn Circ J 1995 Sep
PMID:Fatal cerebral infarction in an asymptomatic young patient with primary antiphospholipid syndrome. 750 May 48

Antiphospholipid antibodies are a diverse group of immunoglobulins initially thought to have specificity to phospholipid epitopes. It is apparent that autoimmune anticardiolipin antibodies require a serum cofactor beta-2-glycoprotein I (beta 2GPI) for their binding to phospholipids. Lupus anticoagulant also may bind to phospholipids by beta 2GPI or by prothrombin. The description of binding to protein-phospholipid epitopes may explain several perplexing features of these antibodies both in vitro and in vivo. Antiphospholipid antibodies have a well-established association with clinical disease--in particular thrombosis, thrombocytopenia and recurrent fetal loss. The mechanism of the predisposition to thrombosis seen with these antibodies is poorly understood. It has been suggested that they may cause endothelial dysfunction by causing increased tissue factor expression, by inhibiting prostacyclin secretion or by inhibiting fibrinolysis. Various platelet-activating activities have also been described. The evidence that antiphospholipid antibodies promote thrombosis by effects on endothelium or platelets is inconclusive. Inhibition of protein C activation, or of activated protein C action, has been demonstrated in vitro. A poor correlation between thrombosis in vivo and these inhibitory effects has been found. Beta-2-glycoprotein I has been identified as a cofactor for binding to phospholipid by thrombogenic anticardiolipin antibodies. That beta 2GPI may be a natural anticoagulant of importance remains to be proved. Inhibition by antiphospholipid antibodies of this anticoagulant function could explain the propensity to thrombosis seen in association with these antibodies.
Baillieres Clin Haematol 1994 Sep
PMID:Antiphospholipid antibodies and thrombosis. 784


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