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https://hdl.handle.net/1959.11/13927
Title: | Low PIP₂ molar fractions induce nanometer size clustering in giant unilamellar vesicles | Contributor(s): | Salvemini, Iyrri (author); Gau, D (author); Reid, Jacqueline (author) ; Bagatolli, Luis A (author); Macmillan, Alexander (author); Moens, Pierre (author) | Publication Date: | 2014 | DOI: | 10.1016/j.chemphyslip.2013.11.003 | Handle Link: | https://hdl.handle.net/1959.11/13927 | Abstract: | Phosphatidylinositol (4,5) bisphosphate (PIP₂) 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 PIP₂ must be able to form localized clusters. In this study, we have used LAURDAN generalized polarization function (GP) with unlabeled PIP₂ and single point fluorescence correlation spectroscopy and brightness analysis of various BODIPY labeled PIP₂ 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 PIP₂, 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 PIP₂ particles with increasing labeled PIP₂ molar fraction. Together with the observed change in LAURDAN GP with increasing molar fraction of unlabeled PIP₂, these results demonstrate the presence of PIP₂ 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 PIP₂ lipids able to move between the liquid ordered and liquid disordered phase. | Publication Type: | Journal Article | Grant Details: | NHMRC/568301 | Source of Publication: | Chemistry and Physics of Lipids, v.177, p. 51-63 | Publisher: | Elsevier Ireland Ltd | Place of Publication: | Ireland | ISSN: | 1873-2941 0009-3084 |
Fields of Research (FoR) 2008: | 029901 Biological Physics 110104 Medical Biochemistry: Lipids 060110 Receptors and Membrane Biology |
Fields of Research (FoR) 2020: | 510501 Biological physics 320504 Medical biochemistry - lipids 310110 Receptors and membrane biology |
Socio-Economic Objective (SEO) 2008: | 970106 Expanding Knowledge in the Biological Sciences | Socio-Economic Objective (SEO) 2020: | 280102 Expanding knowledge in the biological sciences | Peer Reviewed: | Yes | HERDC Category Description: | C1 Refereed Article in a Scholarly Journal |
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Appears in Collections: | Journal Article |
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