Characterization of plasma membrane domains enriched in lipid metabolites

Abstract

A subpopulation of plasma membrane vesicles enriched in membrane lipid metabolites has been isolated from petals of carnation flowers and leaves of canola seedlings. This was achieved by immunopurification from a microsomal membrane preparation using region-specific antibodies raised against a recombinant polypeptide of the plasma membrane H(+)-ATPase. The properties of this subpopulation of vesicles were compared with those of purified plasma membrane isolated by partitioning in an aqueous dextran-polyethylene glycol two-phase system. The lipid composition of the immunopurified vesicles proved to be clearly distinguishable from that of phase-purified plasma membrane, indicating that they represent a unique subpopulation of plasma membrane vesicles. Specifically, the immunopurified vesicles are highly enriched in lipid metabolites, including free fatty acids, diacylglycerol, triacylglycerol and steryl and wax esters, by comparison with the phase-purified plasma membrane. These findings can be interpreted as indicating that lipid metabolites generated within the plasma membrane effectively phase-separate by moving laterally through the plane of the membrane to form discrete domains within the bilayer. It is also apparent that these domains, once formed, are released as vesicles into the cytosol, presumably by microvesiculation from the surface of the plasmalemma. Such removal may be part of normal membrane turnover.

Metabolic Profiling of the Sink-to-Source Transition in Developing Leaves of Quaking Aspen

“…The removal and processing of plastoglobuli rich in fatty acids is thought to prevent chloroplast membrane destabilization in active leaves (Ghosh et al, 1994;Smith et al, 2000). Turnover of phospholipids in plasma membrane vesicles of active plant tissues has also been reported (Madey et al, 2001). …”

Early events in signalling high‐temperature stress in tobacco BY2 cells involve alterations in membrane fluidity and enhanced hydrogen peroxide production

“…Plasma membranes were prepared as described by Madey et al (2001) with some modifications. Cells (30 g fresh weight) were homogenized with a blender in 100 mL homogenization buffer containing 50 mm 4(2-hydroxyethyl)-1-piperazine-ethanesulphonic acid (HEPES)-KOH (pH 7.5), 0.33 m sucrose, 1 mm dithiothreitol (DTT), 0.5 mm phenylmethylsulphonyl fluoride (PMSF), 5 mm ascorbate, 3.6 mm cysteine, 0.6% polyvinylpoly-pyrrolidone (PVPP) and 0.1% bovine serum albumin (BSA).…”

A light‐sensitive mechanism differently regulates transcription and transcript stability of ω3 fatty‐acid desaturases (FAD3, FAD7 and FAD8) in soybean photosynthetic cell suspensions

“…Chloroplasts from soybean cell suspension cultures were obtained as described earlier [11]. Microsomal-enriched membranes were obtained by the method described in [24] with several modifications. The leaf tissue (50 g) was homogenized in 200 ml of homogenization buffer (0.5 M sucrose, 50 mM HEPES-KOH, pH 7.5, 5 mM ascorbate, 3.6 mM cysteine, 0.5 mM PMSF, and 0.6% insoluble PVPP) for 2 min in a Polytron homogenizer.…”