Phospholipid vesicle aggregation: effect of monovalent and divalent ions

Ohki, Shinpei; Düzgüneş, Nejat; Leonards, Kenneth S.

doi:10.1021/bi00538a022

Cited by 146 publications

(103 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…High ionic strength is known to favor aggregation and fusion of cell membranes and lipid vesicles. The threshold concentration of NaCl for the aggregation of vesicles consisting of negatively charged lipids is in the range of 200-500 mM (Ohki et al, 1982;Yishimura & Aki, 1985). The average size of the vesicles, which were formed by CHAPS dialysis, increased with the salt concentration ( Figure 5 ) .…”

Section: Discussionmentioning

confidence: 99%

Functional reconstitution of the nicotinic acetylcholine receptor by CHAPS dialysis depends on the concentrations of salt, lipid, and protein

Schürholz¹,

Kehne²,

Gieselmann³

et al. 1992

Biochemistry

View full text Add to dashboard Cite

ABSTRACT:The detergent CHAPS was found to be the preferable surfactant for the efficient purification and reconstitution of the Torpedo californica nicotinic acetylcholine receptor (AChR). The main result is that the incorporation of the AChR proteins into lipid vesicles by CHAPS dialysis was strongly dependent on the salt and protein concentrations. As monitored by sucrose gradients, by electron microscopy, and by agonist-induced lithium ion flux, the best reconstitution yields were obtained in 0.5 M NaCl at a protein concentration of 0.5 g/L and in 0.84 M NaCl at 0.15 g/L protein. Electron micrographs of receptor molecules, which were incorporated into vesicles, showed single, nonaggregated dimer (M, = 580 000) and monomer (M, = 290 000) species. CHAPS dialysis at NaCl concentrations C0.5 M largely reduced the receptor incorporation concomitant with protein aggregation. Electron micrographs of these preparations revealed large protein sheets or ribbons not incorporated into vesicles. The analysis of static and dynamic light scattering demonstrated that the detergent-solubilized AChR molecules aggregate at low lipid contents (5500 phospholipids/AChR dimer), independent of the salt concentration. AChR proteins eluted from an affinity column with a solution containing 8 mM CHAPS (but no added lipid) still contained 130 f 34 tightly bound phospholipids per dimer. The aggregates (about 10 dimers on the average) could be dissociated by readdition of lipid and, interestingly, also by increasing the CHAPS concentration up to 15 mM. This value is much higher than the CMC of CHAPS = 4.0 f 0.4 mM, which was determined by surface tension measurements. The data clearly suggest protein-micelle interactions in addition to the association of monomeric detergents with proteins. Furthermore, the concentration of the (free) monomeric CHAPS at the vesicle-micelle transformation in 0.5 M NaCl ([Owlc = 3.65 mM) was higher than in 50 mM NaCl ( [Owlc = 2.8 mM). However, it is suggested that the main effect of high salt concentrations durig the reconstitution process is an increase of the fusion (rate) of the ternary protein/lipid/CHAPS complexes with mixed micelles or with vesicular structures, similar to the salt-dependent fusion of vesicles.A necessary and essential step in the detailed characterization of intrinsic membrane proteins is the detergent solubilization and the reconstitution of the protein species in artificial lipid membranes. Impressive examples are channel t We gratefully acknowledge financial support by the Deutsche For-

show abstract

Section: Discussionmentioning

confidence: 99%

Functional reconstitution of the nicotinic acetylcholine receptor by CHAPS dialysis depends on the concentrations of salt, lipid, and protein

Schürholz¹,

Kehne²,

Gieselmann³

et al. 1992

Biochemistry

View full text Add to dashboard Cite

show abstract

“…This could be due to simple Ca 2+ -PS -cross-bridging and/or a more complex process involving adhesion proteins. Further evidence for both options comes from aggregation studies of PS vesicles [40,41], where aggregation occurs in solutions of physiological ionic strength containing Ca 2+ in the mM concentration range. The dependence on high Ca 2+ concentrations and evidence from further studies reporting enhanced aggregation of PS liposomes in the presence of polymers [42] suggest that additional membrane constituents in the RBC contribute to the aggregation process.…”

Section: Signaling Componentsmentioning

confidence: 99%

Stimulation of human red blood cells leads to Ca2+-mediated intercellular adhesion

et al. 2011

View full text Add to dashboard Cite

Red blood cells (RBCs) are a major component of blood clots, which form physiologically as a response to injury or pathologically in thrombosis. The active participation of RBCs in thrombus solidification has been previously proposed but not yet experimentally proven. Holographic optical tweezers and single-cell force spectroscopy were used to study potential cell-cell adhesion between RBCs. Irreversible intercellular adhesion of RBCs could be induced by stimulation with lysophosphatidic acid (LPA), a compound known to be released by activated platelets. We identified Ca 2+ as an essential player in the signaling cascade by directly inducing Ca 2+ influx using A23187. Elevation of the internal Ca 2+ concentration leads to an intercellular adhesion of RBCs similar to that induced by LPA stimulation. Using single-cell force spectroscopy, the adhesion of the RBCs was identified to be approximately 100 pN, a value large enough to be of significance inside a blood clot or in pathological situations like the vasco-occlusive crisis in sickle cell disease patients.

show abstract

“…The influence of these cations on membrane structure and stability has been studied intensively using model lipid bilayers. The addition of salts can trigger lipid bilayer phase separation [1][2][3] and vesicle aggregation and fusion processes [4,5]. The striking influence of the ions has highlighted the importance of lipid-ion interactions in biological processes.…”

Section: Direct Imaging Of Lipid-ion Network Formation Under Physiolomentioning

confidence: 99%

Direct Imaging of Lipid-Ion Network Formation under Physiological Conditions by Frequency Modulation Atomic Force Microscopy

2007

View full text Add to dashboard Cite

Phospholipid vesicle aggregation: effect of monovalent and divalent ions

Cited by 146 publications

References 36 publications

Functional reconstitution of the nicotinic acetylcholine receptor by CHAPS dialysis depends on the concentrations of salt, lipid, and protein

Functional reconstitution of the nicotinic acetylcholine receptor by CHAPS dialysis depends on the concentrations of salt, lipid, and protein

Stimulation of human red blood cells leads to Ca2+-mediated intercellular adhesion

Direct Imaging of Lipid-Ion Network Formation under Physiological Conditions by Frequency Modulation Atomic Force Microscopy

Contact Info

Product

Resources

About