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)

Human apolipoprotein H (ApoH), also called beta 2-glycoprotein I, is a 50-kDa serum glycoprotein whose function is not clearly defined. We have cloned and sequenced ApoH cDNAs both from human liver and from a human hepatoma cell line (HepG2). Both cDNA sequences predict a protein 345 amino acids (aa) in length. This sequence includes a 19-aa hydrophobic, N-terminal signal sequence which is not present in the mature protein [Lozier et al., Proc. Natl. Acad. Sci. USA 81 (1984) 3640-3644]. It differs from this previously reported aa sequence at two positions, both of which strengthen the conservation among the four short consensus repeats within the ApoH molecule. COS-1 cells transiently transfected with the ApoH cDNA in a eukaryotic expression vector produced a single species of ApoH mRNA and secreted in the ApoH protein. The level of ApoH mRNA expressed by HepG2 cells is downregulated by incubation with inflammatory mediators, implying that ApoH is a negative acute-phase protein.
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PMID:Nucleotide sequence and expression of the human gene encoding apolipoprotein H (beta 2-glycoprotein I). 174 14

Human beta 2-glycoprotein I (beta 2-GPI) is involved in cardiolipin (CL) binding of anticardiolipin antibodies (aCL) in systemic lupus erythematosus (SLE). We examined the inter-species differences of beta 2-GPI in alternation of CL binding of aCL. beta 2-GPI preparations were obtained from human, bovine, and rat sera by sequential CL--polyacrylamide affinity, DEAE--cellulose, and anti-human IgG-conjugated Sepharose CL-4B column chromatography, and they had apparent molecular weights of 50, 53, and 55 kDa respectively. Human beta 2-GPI not only enhanced CL binding by aCL in SLE but also depressed it by those in syphilis. Either bovine and rat beta 2-GPI exerted no or quite small inhibition of the binding of syphilitic aCL compared with human beta 2-GPI whereas all three species of beta 2-GPI generated binding of aCL in SLE to a similar degree. Further, a complete cDNA clone, p beta 2-GPI, was isolated from a human hepatoma cell line, HepG2, and its nucleotide sequence was analyzed. The sequences of bovine and rat counterpart molecules (beta 2-GPI) are highly homologous to that of the deduced sequence, and their corresponding regions are 84.0 and 82.5% identical to the complete domain and to the amino acid sequence 53-326 of human beta 2-GPI respectively. One of major differences appears at position 154 in human beta 2-GPI, and might be associated with the inhibitory effect on the binding of syphilitic aCL. The sequencing analysis of these beta 2-GPI proteins might provide leads to functional sites of domains which would be associated with such serological phenomena.
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PMID:Molecular definition of human beta 2-glycoprotein I (beta 2-GPI) by cDNA cloning and inter-species differences of beta 2-GPI in alternation of anticardiolipin binding. 177 18

The effect of sera and purified IgG isolated from plasma of 46 patients with systemic lupus erythematosus (SLE) and 9 healthy donors on the endothelial cell (EC) mediated protein C activation was investigated. Out of the 46 SLE sera used, 19 were antiphospholipid antibodies (aPL) positive. From 12 patients IgG was isolated, of which 6 contained aPL. EC were first incubated with IgG (7 mg/ml) or serum (1:1 diluted) for 1 h and then tested for their ability to promote protein C activation by thrombin, with the cells either in a monolayer or in a suspension. The normal range (mean of control values +/- 2 SD) of protein C activation was 80-120%. In contrast to others, we could not detect an inhibition of protein C activation by any of the patient IgG's or sera. The recently described cofactor for binding of antiphospholipid antibodies to phospholipids, beta 2-glycoprotein I, was purified and added to the purified IgG's. A combination of these two components did not inhibit the EC mediated protein C activation by thrombin. This study suggests that the inhibition of the protein C activation, mediated by EC, is not a general mechanism by which aPL related thrombosis can be explained.
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PMID:In vitro studies of antiphospholipid antibodies and its cofactor, beta 2-glycoprotein I, show negligible effects on endothelial cell mediated protein C activation. 179 12

An anticoagulant protein, factor IX/factor X-binding protein (IX/X-bp), isolated from the venom of Trimeresurus flavoviridis, binds with factor IX and factor X in the presence of Ca2+ with a 1 to 1 stoichiometry (Atoda, H., and Morita, T. (1989) J. Biochem. (Tokyo) 106, 808-813). Analysis of S-pyridylethylated IX/X-bp by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed a 16.0-kDa band (designated the A chain) and a 15.5-kDa band (designated the B chain). These two chains were separated by reversed-phase high performance liquid chromatography, and their complete amino acid sequences were determined by sequencing of the peptides obtained after digestion with lysyl endopeptidase, chymotrypsin, and V8 protease from Staphylococcus aureus and after chemical cleavage with cyanogen bromide. The A chain had an amino-terminal sequence of Asp-Cys-Leu-Ser-Gly- and consisted of 129 residues with Mr 14,830. The B chain has an amino-terminal sequence of Asp-Cys-Pro-Ser-Asp- and consists of 123 residues of Mr 14,440. There was 47% identity between the A and the B chain. The sequence of IX/X-bp showed 25-37% identity with that of the C-type carbohydrate recognition domain-like structure of acorn barnacle lectin, human and rat asialoglycoprotein receptors, the human lymphocyte Fc epsilon receptor for immunoglobulin E, proteoglycan core protein, pancreatic stone protein, and tetranectin. The sequences of the first 18 amino acid residues of both the A and B chains were also, to a certain extent, homologous to the partial amino acid sequence of the b subunit of factor XIII, a member of the beta 2-glycoprotein I-like family. In this region, some similarity with the amino-terminal amino acid sequence of botrocetin was also observed.
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PMID:The primary structure of coagulation factor IX/factor X-binding protein isolated from the venom of Trimeresurus flavoviridis. Homology with asialoglycoprotein receptors, proteoglycan core protein, tetranectin, and lymphocyte Fc epsilon receptor for immunoglobulin E. 183 Nov 97

New details have been added to the description of the antiphospholipid antibody syndrome. These include quantitation of risk of stroke; delineation of an associated acute occlusive vasculopathy syndrome, including its pathology; increased awareness of the association of adrenal insufficiency with antiphospholipid antibody; new demonstration of placental pathology in cases of fetal death; and new details on the persistence or transience of antibody in patients with systemic lupus erythematosus. There are several animal models for the antiphospholipid antibody syndrome. Assay standardization and reproducibility issues, more for the lupus anticoagulant than for the enzyme-linked immunosorbent assay for antiphospholipid antibody, remain as important barriers to progress. Antibody characteristics of activity, isotype, and subclass must be considered in assay interpretation; antigen characteristics of fatty acid chain and lipid phase are also important variables. Other circulating proteins may have clinical importance. Several laboratories have commented that antiphospholipid antibody interferes with protein C. A cofactor, apolipoprotein H, enhances binding of some antiphospholipid IgG antibodies. Other phospholipid-binding proteins are known. Isolation, purification, and perhaps cloning of many of these factors should lead to a better understanding of the pathogenesis of the syndrome.
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PMID:Antiphospholipid antibody and antiphospholipid antibody syndrome. 183 43

Sera were sampled from 83 people (pre- and post-menopausal women and men). Climacteric symptoms of 23 women were treated with conjugated estrogen. Sera were sampled serially until the 21st day of estrogen administration. Serum concentrations of 40 protein components were measured by micro single radial immunodiffusion. The serum proteins were classified into 5 types according to changes after menopause and estrogen therapy, respectively. Type 1 (decreased after menopause and increased by estrogen; alpha 1-antitrypsin, alpha 2-HS - glycoprotein, beta 2-glycoprotein III, Gc-globulin, alpha 1-lipoprotein and alpha 2-AP-glycoprotein), type 2 (unchanged and increased; ceruloplasmin), type 3 (increased and decreased; alpha 1-acid glycoprotein, haptoglobin, serum amyloid P-component, Zn-alpha 2-glycoprotein, beta-lipoprotein and C1-components), type 4 (unchanged and decreased; hemopexin, antithrombin III, beta 2-glycoprotein I, prealbumin and retinol-binding-protein), type 5 (unchanged by estrogen; immunoglobulin M (IgM), IgG and others). Estrogen replacement therapy restored pre-menopausal levels of serum proteins, types 1 and 3. However, estrogen therapy was associated with significantly abnormal levels of proteins, types 2 and 4 in post-menopausal women. Serum levels of type 1 proteins and some type 5 proteins (IgM, alpha 1B-glycoprotein, C9-component and alpha 2-macroglobulin) were higher in pre-menopausal women than in men, whereas type 3 proteins were the opposite.
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PMID:Changes in 40 serum proteins of post-menopausal women. 186 40

A solid-phase sandwich enzyme-linked immunosorbent assay for determining beta 2-glycoprotein I in urine has been developed. It has a working concentration range of 5-40 micrograms/L and a detection limit of approximately 1.4 micrograms/L. The within-plate coefficient of variation (CV) falls between 1.4% and 2.1%, and the between-batch CV ranges from 5.2 to 6.0%. Recovery of beta 2-glycoprotein I added to urine varies between 96 and 110%. The assay can also be used for determining beta 2-glycoprotein I in serum.
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PMID:A sandwich enzyme-linked immunosorbent assay for beta 2-glycoprotein I. 187 76

In order to elucidate the clinical significance of urinary apolipoprotein H (Apo H), otherwise known as beta 2-glycoprotein I, we first developed a non-competitive enzyme immunoassay (EIA) to quantify urinary Apo H levels. The measurable range of this assay was about 2 ng/ml to 100 ng/ml. The intra- and inter-assay coefficients of variation were 2.0 to 4.7% and 8.3 to 17.0%, respectively. These results indicated that this assay had high sensitivity and good reproducibility, and that it was useful for clinical study. We then determined urinary Apo H levels in 24 normal subjects and 36 diabetics using this assay. The mean urinary Apo H index (urinary Apo H/cr ratio), in 20 patients without proteinuria, who were regarded as patients without nephropathy, was 569 +/- 560 (X10(-3) mg/g.cr) and significantly higher than in normal subjects (252 +/- 147, p less than 0.01). The mean urinary Apo H index in 16 patients with overt proteinuria was 1,507 +/- 3,701 and also higher than in normal subjects (p less than 0.01). These results taken collectively indicate that urinary Apo H level using the EIA may be a new sensitive marker for detecting minor change of glomerular basement membrane in diabetics.
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PMID:[Enzyme immunoassay of urinary apolipoprotein H and its application for detecting incipient diabetic nephropathy]. 192 Aug 78

The requirement of plasma cofactor beta 2-glycoprotein I for binding autoantibodies against anionic phospholipids has been reported. We describe the development of an enzyme-linked immunosorbent assay (ELISA) for anti-phospholipid antibodies using highly purified beta 2-glycoprotein I for coating microtitre plates. Intra- and interassay coefficients of variation, determined with serum pools of low, medium and high positivity, ranged between 3% and 18%. 54 sera from patients with systemic lupus erythematosus and related autoimmune disorders were analyzed by this assay; the results correlated well to those obtained in an ELISA using anionic phospholipids on the solid phase (r = 0.85, P less than 0.001). The two ELISA systems showed similar sensitivities although 8/31 positive sera scored negative in the beta 2-glycoprotein I ELISA. The latter group of eight sera showed significantly higher anti-phosphatidylcholine/anti-phosphatidylserine binding ratios than the group of 23 sera which scored positive in both assays. This new assay should permit accurate measurement of most of the clinically relevant anti-phospholipid antibodies and avoid inconsistencies likely to arise from secondary interactions that characterize lipid-based ELISA.
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PMID:Measurement of anti-phospholipid antibodies by ELISA using beta 2-glycoprotein I as an antigen. 194 Mar 91

The binding of affinity-purified anticardiolipin antibodies (ACA) to liposomes that contained cardiolipin or phosphatidylserine was investigated. ACA bound to these liposomes only in the presence of plasma or serum, which indicated a requirement for a plasma component. This component--referred to as aca-cofactor--was purified; its activity to support ACA binding to liposomes that contained cardiolipin was not destroyed by heat (10 min at 90 degrees C), but was greatly diminished on incubation with trypsin. aca-cofactor bound liposomes that contained negatively charged phospholipid but had no affinity for liposomes that contained neutral phospholipid (eg, phosphatidylcholine); this binding was independent of calcium ions. aca-cofactor was essential for ACA to bind to liposomes that contained cardiolipin or phosphatidylserine and, when coated on a microtitre plate in the absence of any phospholipid, aca-cofactor was an apparent antigen for ACA in an enzyme-linked immunosorbent assay. aca-cofactor is a single chain polypeptide with an apparent molecular weight of 50 kD (non-reduced), which increases to 70 kD upon reduction, and its properties closely resemble those of beta 2-glycoprotein I (apolipoprotein H).
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PMID:Anticardiolipin antibodies (ACA) directed not to cardiolipin but to a plasma protein cofactor. 197 70


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