Annexin A5 (or annexin V) is a cellular protein in the annexin group. In flow cytometry, annexin V is commonly used to detect apoptotic cells by its ability to bind to phosphatidylserine, a marker of apoptosis when it is on the outer leaflet of the plasma membrane. The function of the protein is unknown; however, annexin A5 has been proposed to play a role in the inhibition of blood coagulation by competing for phosphatidylserine binding sites with prothrombin and also to inhibit the activity of phospholipase A1. These properties have been found by in vitro experiments.
Antibodies directed against annexin A5 are found in patients with a disease called the antiphospholipid syndrome (APS), a thrombophilic disease associated with autoantibodies against phospholipid compounds.
Annexin A5 forms a shield around negatively charged phospholipid molecules. The formation of an annexin A5 shield blocks the entry of phospholipids into coagulation (clotting) reactions. In the antiphospholipid antibody syndrome, the formation of the shield is disrupted by antibodies. Without the shield, there is an increased quantity of phospholipid molecules on cell membranes, speeding up coagulation reactions and causing the blood-clotting characteristic of the antiphospholipid antibody syndrome.
Annexin A5 showed upregulation in papillary thyroid carcinoma.
Annexin A5 is used as a non-quantitative probe to detect cells that have expressed phosphatidylserine (PS) on the cell surface, an event found in apoptosis as well as other forms of cell death.Platelets also expose PS and PE on their surface when activated, which serves as binding site for various coagulation factors.
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1bc3: RECOMBINANT RAT ANNEXIN V, TRIPLE MUTANT (T72K, S144K, S228K)
1bcw: RECOMBINANT RAT ANNEXIN V, T72A MUTANT
1bcy: RECOMBINANT RAT ANNEXIN V, T72K MUTANT
1bcz: RECOMBINANT RAT ANNEXIN V, T72S MUTANT
1g5n: ANNEXIN V COMPLEX WITH HEPARIN OLIGOSACCHARIDES
1hak: CRYSTAL STRUCTURE OF RECOMBINANT HUMAN PLACENTAL ANNEXIN V COMPLEXED WITH K-201 AS A CALCIUM CHANNEL ACTIVITY INHIBITOR
1hvd: STRUCTURAL AND ELECTROPHYSIOLOGICAL ANALYSIS OF ANNEXIN V MUTANTS. MUTAGENESIS OF HUMAN ANNEXIN V, AN IN VITRO VOLTAGE-GATED CALCIUM CHANNEL, PROVIDES INFORMATION ABOUT THE STRUCTURAL FEATURES OF THE ION PATHWAY, THE VOLTAGE SENSOR AND THE ION SELECTIVITY FILTER
1hve: STRUCTURAL AND ELECTROPHYSIOLOGICAL ANALYSIS OF ANNEXIN V MUTANTS. MUTAGENESIS OF HUMAN ANNEXIN V, AN IN VITRO VOLTAGE-GATED CALCIUM CHANNEL, PROVIDES INFORMATION ABOUT THE STRUCTURAL FEATURES OF THE ION PATHWAY, THE VOLTAGE SENSOR AND THE ION SELECTIVITY FILTER
1hvf: STRUCTURAL AND ELECTROPHYSIOLOGICAL ANALYSIS OF ANNEXIN V MUTANTS. MUTAGENESIS OF HUMAN ANNEXIN V, AN IN VITRO VOLTAGE-GATED CALCIUM CHANNEL, PROVIDES INFORMATION ABOUT THE STRUCTURAL FEATURES OF THE ION PATHWAY, THE VOLTAGE SENSOR AND THE ION SELECTIVITY FILTER
1hvg: STRUCTURAL AND ELECTROPHYSIOLOGICAL ANALYSIS OF ANNEXIN V MUTANTS. MUTAGENESIS OF HUMAN ANNEXIN V, AN IN VITRO VOLTAGE-GATED CALCIUM CHANNEL, PROVIDES INFORMATION ABOUT THE STRUCTURAL FEATURES OF THE ION PATHWAY, THE VOLTAGE SENSOR AND THE ION SELECTIVITY FILTER
1n41: Crystal Structure of Annexin V K27E Mutant
1n42: Crystal Structure of Annexin V R149E Mutant
1n44: Crystal Structure of Annexin V R23E Mutant
1sav: HUMAN ANNEXIN V WITH PROLINE SUBSTITUTION BY THIOPROLINE
2ie6: Annexin V under 2.0 MPa pressure of xenon
2ie7: Annexin V under 2.0 MPa pressure of nitrous oxide
2ran: RAT ANNEXIN V CRYSTAL STRUCTURE: CA2+-INDUCED CONFORMATIONAL CHANGES