title: Highly sensitive and stable phosphatidylserine liposome aggregation assay for annexins.
abstract: Annexins are a gene family of Ca(2+)-dependent membrane binding proteins which interact specifically with acidic phospholipids. We describe here details of highly sensitive and precise assays for annexins I and V, utilizing turbidometric analysis of phosphatidylserine liposome aggregation. In the case of annexin I, the new assay is 7-fold more sensitive than the conventional chromaffin granule aggregation assay in terms of threshold for detection and the rate of increase of initial absorbance is 15-fold greater. Annexin V, which binds but does not aggregate liposomes, can be assayed on the basis of inhibition of Ca(2+)-dependent liposome aggregation. Further comparative advantages of the assay include lower expense and increased shelf life of the liposome reagent.
authors.affiliation: Laboratory of Cell Biology and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: G
authors.initials: G
authors.lastname: Lee
authors.forename: H B
authors.initials: HB
authors.lastname: Pollard
mesh_terms: D000818:Animals; D017305:Annexin A1 / Q000032:analysis* / Q000378:metabolism; D017304:Annexin A5 / Q000032:analysis* / Q000378:metabolism; D001671:Biochemistry / Q000191:economics / Q000379:methods; D002118:Calcium / Q000378:metabolism; D002417:Cattle; D002837:Chromaffin Granules / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry* / Q000378:metabolism; D009391:Nephelometry and Turbidimetry / Q000379:methods; D010718:Phosphatidylserines / Q000737:chemistry* / Q000378:metabolism; D012680:Sensitivity and Specificity; D013053:Spectrophotometry / Q000191:economics / Q000379:methods* / Q000592:standards
chemical_list: D017305:Annexin A1; D017304:Annexin A5; D008081:Liposomes; D010718:Phosphatidylserines; D002118:Calcium