Annexin A5

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annexin A5
Identifiers
Symbol	ANXA5 ENX2, ANX5
HUGO	543
Entrez	308
OMIM	131230
RefSeq	NM_001154
UniProt	P08758
Other data
Locus	Chr. 4 q27

Annexin A5 is a cellular protein in the Annexin group. 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 also by competing for phosphatidylserine binding sites. These properties have been found by in vitro experiments (in a test tube) and they have not been confirmed by experiments with laboratory annimals

Antibodies directed against annexin A5 are the cause of a syndrome called the Antiphospholipid syndrome.

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 is used as a probe in the annexin A5 affinity assay to detect cells which have expressed phosphatidylserine on the cell surface, a feature found in apoptosis as well as other forms of cell death.More info click link below: http://imoax1.unimo.it/~cossarizza/apobook98/chap16.htm