首页|Low PIP_2 molar fractions induce nanometer size clustering in giant unilamellar vesicles

Low PIP_2 molar fractions induce nanometer size clustering in giant unilamellar vesicles

扫码查看
原文链接
  • NSTL
  • Elsevier
Phosphatidylinositol (4,5) bisphosphate (PIP_2) is an important signaling molecule located on the inner leaflet of the cell membrane. In order to perform its various signaling functions, it is suggested that PIP_2 must be able to form localized clusters. In this study, we have used LAURDAN generalized polarization function (GP) with unlabeled PIP_2 and single point fluorescence correlation spectroscopy and brightness analysis of various BODIPY labeled PIP_2 to determine the presence of clusters in the membrane of giant unilamellar vesicles (GUVs) made of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) or a mixture of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), sphingomyelin and cholesterol. We determined the number of freely diffusing fluorescent BODIPY molecules in the membrane and found that in GUVs containing various amounts of labeled PIP_2, this number was significantly lower than in GUVs made with the control BODIPY labeled hexadecyl phosphatidylcholine (BODIPY-HPC). Also, we noted an increase in brightness of the labeled PIP_2 particles with increasing labeled PIP_2 molar fraction. Together with the observed change in LAURDAN GP with increasing molar fraction of unlabeled PIP_2, these results demonstrate the presence of PIP_2 enriched clusters that are smaller than the resolution limit of the fluorescent microscope. In addition, we report the presence of a hypsochromic shift of the fluorescence for the BODIPY labeled lipids that we attributed to clustering. This clustering result in a change in the partitioning of the lipids with the BODIPY labeled PIP_2 lipids able to move between the liquid ordered and liquid disordered phase.

PhosphatidylinositolFCSBODIPYNumber and brightness analysis

Iyrri L. Salvemini、D.M. Gau、J. Reid、L.A. Bagatolli、A. Macmillan、P.D.J. Moens

展开 >

Centre for Bioactive Discovery in Health and Ageing, School of Science & Technology, University of New England, Armidale, NSW 2351, Australia

Membrane Biophysics and Biophotonics Group/MEMPHYS-Center for Biomembrane Physics, Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark

Biomedical Imaging Facility, Mark Wainwright Analytical Centre, the University of New South Wales, Sydney, NSW, Australia

2014

10.1016/j.chemphyslip.2013.11.003

Chemistry and Physics of Lipids

Chemistry and Physics of Lipids

SCI
ISSN：0009-3084
年,卷(期)：2014.177
  • 14
  • 36