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

A1 Originalartikel i en vetenskaplig tidskrift (referentgranskad)


Interna författare/redaktörer


Publikationens författare: Mattjus P, Pike HM, Molotkovsky JG, Brown RE
Förläggare: AMER CHEMICAL SOC
Publiceringsår: 2000
Tidskrift: Biochemistry
Tidskriftsakronym: BIOCHEMISTRY-US
Volym: 39
Nummer: 5
Artikelns första sida, sidnummer: 1067
Artikelns sista sida, sidnummer: 1075
Antal sidor: 9
ISSN: 0006-2960
eISSN: 1520-4995


Abstrakt

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.

Senast uppdaterad 2019-06-12 vid 06:06