Annexin A5

Annexin A5
250px PDB rendering based on 1a8a.
Available structures PDB Ortholog search: PDBe, RCSB List of PDB id codes 1ANW, 1ANX, 1AVH, 1AVR, 1HAK, 1HVD, 1HVE, 1HVF, 1HVG, 1SAV, 2XO2, 2XO3
Identifiers
Symbols	ANXA5 ; ANX5; ENX2; HEL-S-7; PP4; RPRGL3
External IDs	OMIM: 131230 MGI: 106008 HomoloGene: 20312 GeneCards: ANXA5 Gene
Gene ontology Molecular function • phospholipase inhibitor activity • calcium ion binding • phospholipid binding • calcium-dependent phospholipid binding • peptide hormone binding • receptor tyrosine kinase binding Cellular component • intracellular • nucleus • cytoplasm • focal adhesion • external side of plasma membrane • intercalated disc • membrane • Z disc • sarcolemma • cell projection • extracellular exosome • endothelial microparticle Biological process • positive regulation of defense response to virus by host • signal transduction • blood coagulation • response to organic substance • negative regulation of blood coagulation • positive regulation of apoptotic process • negative regulation of apoptotic process • negative regulation of catalytic activity • protein homooligomerization • response to calcium ion • activation of mitophagy in response to mitochondrial depolarization • regulation of sperm motility Sources: Amigo / QuickGO
RNA expression pattern
File:PBB GE ANXA5 200782 at tn.png
More reference expression data
Orthologs
Species	Human	Mouse
Entrez	308	11747
Ensembl	ENSG00000164111	ENSMUSG00000027712
UniProt	P08758	P48036
RefSeq (mRNA)	NM_001154	NM_009673
RefSeq (protein)	NP_001145	NP_033803
Location (UCSC)	Chr 4: 121.67 – 121.7 Mb	Chr 3: 36.45 – 36.48 Mb
PubMed search	[1]	[2]

Annexin A5 (or annexin V) 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. These properties have been found by in vitro experiments.

Pathology

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.

Laboratory use

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.

The annexin A5 affinity assay typically uses a conjugate of annexin V and a fluorescent or enzymatic label, biotin or other tags, or a radioelement, in a suitable buffer (annexin V binding to aminophospholipids is Ca²⁺ dependent). The assay combines annexin V staining of PS and PE membrane events with the staining of DNA in the cell nucleus with propidium iodide (PI) or 7-Aminoactinomycin D (AAD-7), distinguishing viable cells from apoptotic cells and necrotic cells. Detection occurs by flow cytometry or a fluorescence microscope.

Interactions

Annexin A5 has been shown to interact with Kinase insert domain receptor and Integrin, beta 5.

External links

• Annexin A5 at the US National Library of Medicine Medical Subject Headings (MeSH)