Aarhus University Seal / Aarhus Universitets segl

Lactadherin binds to phosphatidylserine-containing vesicles in a two-step mechanism sensitive to vesicle size and composition

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaperJournal articleResearchpeer-review


  • Article

    Final published version, 681 KB, PDF document


  • Daniel Otzen
  • Kristine Blans, Denmark
  • Huabing Wang, Denmark
  • Gary E Gilbert, Medicine Departments of VA Boston Healthcare System, Brigham and Women's Hospital, and Harvard Medical School, United States
  • Jan T Rasmussen
Lactadherin binds to phosphatidylserine (PS) in a stereospecific and calcium independent manner that is promoted by vesicle curvature. Because membrane binding of lactadherin is supported by a PS content of as little as 0.5%, lactadherin is a useful marker for cell stress where limited PS is exposed, as well as for apoptosis where PS freely traverses the plasma membrane. To gain further insight into the membrane-binding mechanism, we have utilized intrinsic lactadherin fluorescence. Our results indicate that intrinsic fluorescence increases and is blue-shifted upon membrane binding. Stopped-flow kinetic experiments confirm the specificity for PS and that the C2 domain contains a PS recognition motif. The stopped-flow kinetic data are consistent with a two-step binding mechanism, in which initial binding is followed by a slower step that involves either a conformational change or an altered degree of membrane insertion. Binding is detected at concentrations down to 0.03% PS and the capacity of binding reaches saturation around 1% PS (midpoint 0.15% PS). Higher concentrations of PS (and also to some extent PE) increase the association kinetics and the affinity. Increasing vesicle curvature promotes association. Remarkably, replacement of vesicles with micelles destroys the specificity for PS lipids. We conclude that the vesicular environment provides optimal conditions for presentation and recognition of PS by lactadherin in a simple binding mechanism. This article is part of a Special Issue entitled: Protein Folding in Membranes.
Original languageEnglish
JournalBBA General Subjects
Pages (from-to)1019-1027
Number of pages9
Publication statusPublished - Apr 2012

See relations at Aarhus University Citationformats

Download statistics

No data available

ID: 48904535