title: Annexin V perturbs or stabilises phospholipid membranes in a calcium-dependent manner.
abstract: The potency of annexin V to transport Ca2+ ions across phospholipid membranes was investigated, using large unilamellar phospholipid vesicles loaded with the Ca2+ indicator fura-2. It was demonstrated that annexin V leaves the vesicle membranes intact when added in the presence of 1 mM Ca2+. However, if the vesicles were first incubated with annexin V in the absence of Ca2+, subsequent addition of Ca2+ produced a fluorescence signal due to binding of Ca2+ to fura-2. Centrifugation of the vesicle suspension immediately thereafter showed that this signal originated from the supernatant and not from the sedimented vesicles. Our results show that annexin V causes loss of vesicle integrity in the absence of Ca2+, and leakage of trapped fura-2, rather than inward Ca2+ transport. Bovine serum albumin or Ca2+ concentrations higher than 2.5 mM also caused such fura-2 leakage. Apparently, calcium-dependent binding of annexin V to the membrane prevents aspecific membrane damage caused by this protein.
authors.affiliation: Cardiovascular Research Institute Maastricht (CARIM), University of Limburg, Maastricht, The Netherlands.
authors.forename: E L
authors.initials: EL
authors.lastname: Goossens
authors.forename: C P
authors.initials: CP
authors.lastname: Reutelingsperger
authors.forename: F H
authors.initials: FH
authors.lastname: Jongsma
authors.forename: R
authors.initials: R
authors.lastname: Kraayenhof
authors.forename: W T
authors.initials: WT
authors.lastname: Hermens
mesh_terms: D017304:Annexin A5 / Q000502:physiology*; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D008563:Membrane Lipids / Q000378:metabolism; D010743:Phospholipids / Q000378:metabolism*
chemical_list: D017304:Annexin A5; D015220:Calcium Channels; D008563:Membrane Lipids; D010743:Phospholipids; D002118:Calcium