Charged membrane surfaces impede the protein-mediated transfer of glycosphingolipids between phospholipid bilayers

A1 Journal article (refereed)


Internal Authors/Editors


Publication Details

List of Authors: Mattjus P, Pike HM, Molotkovsky JG, Brown RE
Publisher: AMER CHEMICAL SOC
Publication year: 2000
Journal: Biochemistry
Journal acronym: BIOCHEMISTRY-US
Volume number: 39
Issue number: 5
Start page: 1067
End page: 1075
Number of pages: 9
ISSN: 0006-2960
eISSN: 1520-4995


Abstract

A lipid transfer protein that facilitates the transfer of glycolipids between donor and acceptor membranes has been investigated using a fluorescence resonance energy transfer assay. The glycolipid transfer protein (23-24 kDa, pI 9.0) catalyzes the high specificity transfer of lipids that have sugars beta-linked to either a ceramide or a diacylglycerol backbone, such as simple glycolipids and gangliosides, but not the transfer of phospholipids, cholesterol, or cholesterol esters. In this study, we examined the effect of different charged lipids on the rate of transfer of anthrylvinyl-labeled galactosylceramide (1 mol %) from a donor to acceptor vesicle population at neutral pH. Compared to neutral donor vesicle membranes, introduction of negatively charged lipid at 5 or 10 mol % into the donor vesicles significantly decreased the transfer rate. Introduction of the same amount of negative charge into the acceptor vesicle membrane did not impede the transfer rate as effectively. Also, positive charge in the donor vesicle membrane was not as effective at slowing the transfer rate as was negative charge in the donor vesicle. Increasing the ionic strength of the buffer with NaCl significantly reversed the charge effects. At neutral pH, the transfer protein (pI congruent to 9.0) is expected to be positively charged, which may promote association with the negatively charged donor membrane. Based on these and other experiments, we conclude that the transfer process follows first-order kinetics and that the off-rate of the transfer protein from the donor vesicle surface is the rate-limiting step in the transfer process.

Last updated on 2019-22-09 at 05:18