Beta-2-glycoprotein 1 (APOH)
The protein contains 345 amino acids for an estimated molecular weight of 38298 Da.
Binds to various kinds of negatively charged substances such as heparin, phospholipids, and dextran sulfate. May prevent activation of the intrinsic blood coagulation cascade by binding to phospholipids on the surface of damaged cells. (updated: March 4, 2015)
Protein identification was indicated in the following studies:
- Goodman and co-workers. (2013) The proteomics and interactomics of human erythrocytes. Exp Biol Med (Maywood) 238(5), 509-518.
- Hegedűs and co-workers. (2015) Inconsistencies in the red blood cell membrane proteome analysis: generation of a database for research and diagnostic applications. Database (Oxford) 1-8.
- Bryk and co-workers. (2017) Quantitative Analysis of Human Red Blood Cell Proteome. J Proteome Res. 16(8), 2752-2761.
- D'Alessandro and co-workers. (2017) Red blood cell proteomics update: is there more to discover? Blood Transfus. 15(2), 182-187.
Methods
The following articles were analysed to gather the proteome content of erythrocytes.
The gene or protein list provided in the studies were processed using the ID mapping API of Uniprot in September 2018. The number of proteins identified and mapped without ambiguity in these studies is indicated below.
Only Swiss-Prot entries (reviewed) were considered for protein evidence assignation.
| Publication | Identification 1 | Uniprot mapping 2 | Not mapped / Obsolete | TrEMBL | Swiss-Prot |
|---|---|---|---|---|---|
| Goodman (2013) | 2289 (gene list) | 2278 | 53 | 20599 | 2269 |
| Lange (2014) | 1234 | 1234 | 7 | 28 | 1224 |
| Hegedus (2015) | 2638 | 2622 | 0 | 235 | 2387 |
| Wilson (2016) | 1658 | 1528 | 170 | 291 | 1068 |
| d'Alessandro (2017) | 1826 | 1817 | 2 | 0 | 1815 |
| Bryk (2017) | 2090 | 2060 | 10 | 108 | 1942 |
| Chu (2018) | 1853 | 1804 | 55 | 362 | 1387 |
1 as available in the article and/or in supplementary material
2 uniprot mapping returns all protein isoforms as one entry
The compilation of older studies can be retrieved from the Red Blood Cell Collection database.
The data and differentiation stages presented below come from the proteomic study and analysis performed by our partners of the GReX consortium, more details are available in their published work.
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Biological Process
Blood coagulation, intrinsic pathway
Negative regulation of angiogenesis
Negative regulation of blood coagulation
Negative regulation of endothelial cell migration
Negative regulation of endothelial cell proliferation
Negative regulation of fibrinolysis
Negative regulation of myeloid cell apoptotic process
Negative regulation of smooth muscle cell apoptotic process
Plasminogen activation
Platelet degranulation
Positive regulation of blood coagulation
Positive regulation of lipoprotein lipase activity
Regulation of fibrinolysis
Triglyceride metabolic process
Triglyceride transport
The reference OMIM entry for this protein is 138700
Apolipoprotein h; apoh
Glycoprotein i, beta-2; b2gp1
Glycoprotein 1, beta-2
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DESCRIPTION
The APOH gene encodes beta-2 glycoprotein I, also known as apolipoprotein H, a single-chain plasma protein of about 50 kD. Beta-2 GPI binds to and neutralizes negatively charged phospholipid macromolecules, thereby diminishing inappropriate activation of the intrinsic blood coagulation cascade. Beta-2 GPI has been implicated in a variety of physiologic pathways, including blood coagulation, hemostasis, and the production of antiphospholipid antibodies characteristic of antiphospholipid syndrome (APS; 107320) (summary by Mehdi et al., 2003).CLONING
Lozier et al. (1984) determined the full amino acid sequence of beta-2-glycoprotein (apoH). The deduced 326-amino acid protein contains 5 attached glucosamine-containing oligosaccharides. Computerized analysis of the sequence revealed 5 consecutive homologous segments in which cysteine, proline, and tryptophan appeared to be highly conserved. Mehdi et al. (1991) cloned and sequenced APOH cDNAs from human liver and from a human hepatoma cell line. Both cDNAs predicted a protein of 345 amino acids, including a 19-amino acid hydrophobic, N-terminal signal sequence that is not present in the mature protein. The level of APOH mRNA expressed by the hepatoma cells was downregulated by incubation with inflammatory mediators, implying that APOH is a negative acute-phase protein. By Northern blot analysis, Steinkasserer et al. (1992) established that APOH is synthesized in the liver where a transcript of approximately 1.5 kb was identified. Sanghera et al. (2001) found that the chimpanzee APOH gene encodes a deduced 326-amino acid protein, as in humans. The human and chimpanzee APOH proteins share 99.4% sequence similarity.GENE STRUCTURE
Sheng et al. (1997) found that the mouse Apoh gene contains 8 exons and spans approximately 18 kb. Sanghera et al. (2001) found that the chimpanzee APOH gene, like the human gene, contains 8 exons.MAPPING
Haagerup et al. (1991) demonstrated RFLPs in the APOH gene and used these in CEPH family studies to locate the gene on 17q. The marker that showed closest linkage was HOX2 (142960), located at 17q21-q22; lod score = 8.83 at theta = 0.05. Linkage to COL1A1 (120150) was indicated by a lod score of 6.18 at theta = 0.12. By hybridizing a cDNA probe for APOH to a panel of somatic cell hybrids, Steinkasserer et al. (1992) showed that the structural locus maps to 17q23-qter. Nonaka et al. (1992) mapped the mouse Apoh gene to chromosome 11. Nonaka et al. (1992) commented that the mouse Apoh protein is composed of 5 repeating units called short consensus repeats (SCR), which are found mostly in the regulatory proteins of the complement system.GENE FUNCTION
Nakaya et al. (1980) demonstrated beta-2-glycoprotein I activation of lipoprotein lipase and designated this glycoprotein as apolipoprotein H. Lozier et al. (1984) noted that B2GI is associated with lipoproteins, binds to platelets, interacts with heparin, and may be involved in blood coagulation. McNeil et al. (1990) identified beta-2-glycoprotein I as a cofactor required for antiphospholipid antibodies (APA) to bind to cardiolipin. These findings suggested that APA are directed against a complex antigen that includes B2GPI. In addition, B2GPI bound to anionic phospholipids in the absence of anticardiolipin antibodies. McNeil et al. (1990) hypothesized that anticardiolipin APA may interfere with the function of apoH in vivo, which may explain the associat ... More on the omim web site
Feb. 2, 2018: Protein entry updated
Automatic update: Uniprot description updated
Dec. 19, 2017: Protein entry updated
Automatic update: Uniprot description updated
Nov. 23, 2017: Protein entry updated
Automatic update: Uniprot description updated
June 20, 2017: Protein entry updated
Automatic update: comparative model was added.
March 16, 2016: Protein entry updated
Automatic update: OMIM entry 138700 was added.
Jan. 27, 2016: Protein entry updated
Automatic update: model status changed
Jan. 24, 2016: Protein entry updated
Automatic update: model status changed