Diffusion coefficient of fluorescent phosphatidylinositol 4,5-bisphosphate in the plasma membrane of cells

Phosphatidylinositol 4,5-bisphosphate (PIP(2)) controls a surprisingly large number of processes in cells. Thus, many investigators have suggested that there might be different pools of PIP(2) on the inner leaflet of the plasma membrane. If a significant fraction of PIP(2) is bound electrostatically...

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Bibliographic Details
Published in:Molecular biology of the cell 2008-04, Vol.19 (4), p.1663-1669
Main Authors: Golebiewska, Urszula, Nyako, Marian, Woturski, William, Zaitseva, Irina, McLaughlin, Stuart
Format: Article
Language:English
Subjects:
Animals
Boron Compounds
Cell Line
Cell Membrane - metabolism
Diffusion
Epithelial Cells - metabolism
Fibroblasts - metabolism
Fluorescent Dyes
Humans
Membranes, Artificial
Microscopy, Confocal
Phosphatidylinositol 4,5-Diphosphate - metabolism
Phosphoinositide Phospholipase C - metabolism
Rats
Rhodamines
Spectrometry, Fluorescence
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Summary:Phosphatidylinositol 4,5-bisphosphate (PIP(2)) controls a surprisingly large number of processes in cells. Thus, many investigators have suggested that there might be different pools of PIP(2) on the inner leaflet of the plasma membrane. If a significant fraction of PIP(2) is bound electrostatically to unstructured clusters of basic residues on membrane proteins, the PIP(2) diffusion constant, D, should be reduced. We microinjected micelles of Bodipy TMR-PIP(2) into cells, and we measured D on the inner leaflet of fibroblasts and epithelial cells by using fluorescence correlation spectroscopy. The average +/- SD value from all cell types was D = 0.8 +/- 0.2 microm(2)/s (n = 218; 25 degrees C). This is threefold lower than the D in blebs formed on Rat1 cells, D = 2.5 +/- 0.8 microm(2)/s (n = 26). It is also significantly lower than the D in the outer leaflet or in giant unilamellar vesicles and the diffusion coefficient for other lipids on the inner leaflet of these cell membranes. The simplest interpretation is that approximately two thirds of the PIP(2) on inner leaflet of these plasma membranes is bound reversibly.
ISSN:1059-1524
1939-4586
DOI:10.1091/mbc.e07-12-1208