Mechanism of the spontaneous transfer of phospholipids between bilayers

Abstract

A fluorescent phospholipid, 1-palmitoyl-2-pyrenedecanoylphosphatidylcholine, was used to study the mechanism of spontaneous phospholipid transfer between single-walled phospholipid vesicles. The half-time for transfer of this molecule between vesicles of dimyristoylphosphatidylcholine at 36 degrees C is 13 h if flip-flop is negligible or 24 h if flip-flop is faster than intervesicle exchange. The half-time is unaffected by the concentration of acceptor vesicles, which indicates that transfer of label takes place by diffusion of monomers or micelles through the aqueous phase rather than by collision of vesicles. These results are compared with previous studies of spontaneous lipid transfer.

The integrity of the α-helical domain of intestinal fatty acid binding protein is essential for the collision-mediated transfer of fatty acids to phospholipid membranes

“…A plot of 1/ΔF versus (1/ΔFmax)([SUV]/[FABP]) gives a slope of 1/Kp. The partition coefficient was used to establish AOFA transfer assay conditions so as to ensure essentially unidirectional transfer [22].…”

Spontaneous lipid transfer between organized lipid assemblies

“…[17][18][19][20][21][22]. and with lipids bearing fluorescent dyes (e.g., [23][24][25][26][27][28][29][30]. While one might argue that inserting lipids into membranes is better achieved using soluble lipid transfer proteins.…”

“…The mechanism by which spontaneous lipid transfer occurs between membranes has been investigated in many independent laboratories [23,26,57,66,[110][111][112][113][114][132][133][134][135]. In the vast majority of cases, it has been concluded that the transfer event is a first-order process in which the rate-limiting step is desorption of lipid molecules from the donor membrane surface followed by rapid diffusion through the aqueous phase to an acceptor membrane (Fig.…”

“…However, as was pointed out above, the majority of experimental data reported prior to 1988 argued against such a mechanism of lipid transfer (e.g., Refs. 23,26,57,66,[110][111][112][113][114][132][133][134][135]. Then, two different laboratories both reported increased spontaneous lipid transfer rates attributable to transient collisions between donor and acceptor surfaces [96][97][98][107][108][109].…”

Properties of the binding sites for the sn-1 and sn-2 acyl chains on the phosphatidylinositol transfer protein from bovine brain

“…These lipids carry a pyrenylacyl chain in either the sn-1 or sn-2 position and an unlabeled acyl chain in the other position. Similar lipids have been used by others to study either passive or protein-mediated phospholipid transfer (Charlton et al, 1978;Doody et al, 1980;Roseman & Thompson, 1980;Massey et al, 1982Massey et al, , 1984Massey et al, , 1985. By varying the position and the length of the pyrenylacyl and unlabeled acyl chain, one can systematically probe the sn-1 and sn-2 acyl binding sites of the protein.…”