Formation of large, membrane skeleton-free erythrocyte vesicles as a function of the intracellular pH and temperature

Lelkes, G; Fodor, I.

doi:10.1016/0005-2736(91)90223-u

Cited by 13 publications

(4 citation statements)

References 37 publications

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“…Erythrocytes washed with pH 5.5 buffer become slightly cupped (MI = -0.75) at room temperature. Upon warming to 37 °C, these cells undergo a irreversible shape transformation which involves bleb formation and severe stomatocytosis (Lelkes & Fodor, 1991; Yang and Huestis, unpublished results). To examine the role of this shape change on lipid transfer, cells at pH 5.5 were fixed in 0.14% glutaraldehyde for 10 min at room temperature.…”

Section: A23187mentioning

confidence: 98%

Mechanism of intermembrane phosphatidylcholine transfer: Effects of pH and membrane configuration

Yang¹,

Huestis²

1993

Biochemistry

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The mechanism of phospholipid transfer between membranes has been studied as a function of the configuration and concentration of donor and recipient membranes. The study was motivated by the observation that dimyristoylphosphatidylcholine transfers from sonicated vesicles to erythrocytes at a 4-fold faster rate at pH 5.5 than at pH 7.4. It is unexpected that the solubility of phosphatidylcholine should be affected by pH changes in this range; indeed, the more hydrophilic homolog dilauroylphosphatidylcholine transfers at closely similar rates at pH 5.5 and 7.4. The behavior of the more hydrophobic lipid is not consistent with transfer solely as a monomer passing through the aqueous phase. The effects of membrane proximity on phospholipid transfer were examined in dilution experiments employing intact erythrocytes, resealed ghosts, erythrocyte membrane buds, and sonicated vesicles as both donor and recipient membranes. For both hydrophobic and less hydrophobic lipids, the kinetics of intermembrane transfer were affected significantly by dilution at constant donor:recipient ratios. The results were fit to a kinetic model containing contributions from both through-solution monomer transfer and transient collisional transfer. The model predicts that the mechanism of intermembrane transfer varies with experimental conditions such as membrane concentration, donor and acceptor membrane area, and surface curvature. Through-solution monomer transfer predominates for less hydrophobic lipids at all values of pH and membrane concentration, and for more hydrophobic lipids at very high membrane dilutions. Transient collisional transfer contributes significantly to the rate for relatively hydrophobic lipids in concentrated donor-acceptor systems, an effect that is particularly evident at pH values below 6. The size and surface configuration of donor and recipient membranes also alter the relative contributions of through-solution and collisional transfer.

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Section: A23187mentioning

confidence: 98%

Mechanism of intermembrane phosphatidylcholine transfer: Effects of pH and membrane configuration

Yang¹,

Huestis²

1993

Biochemistry

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“…Also, it is known that exposure to these molecular species will i) lower the onset temperature for thermally induced dissociation of spectrin network components (Streichman et al, 1988;Smith and Palek, 1980), ii) affect the membrane deformability and stability of erythrocytes as measured by ektacytometry (Chasis and Mohandas, 1986), iii) weaken the spectrin-skeleton protein complexes based on the dissociation of protein complexes (Sheetz and Casaly, 1980), or iv) increase integral protein lateral mobility (Schindler et al, 1980). Finally, wheat germ agglutinin (WGA) is known to i) enhance binding of spectrin to glycophorin in the plasma membrane (Chasis et al, 1985;Chasis and Schrier, 1989), ii) inhibit temperature-induced and pH-induced vesiculation (Lelkes and Fodor, 1991), and iii) block shape changes from occurring (Lovrien and Anderson, 1980).…”

Section: Effects Of Membrane Skeleton Agentsmentioning

confidence: 99%

Surface shape change during fusion of erythrocyte membranes is sensitive to membrane skeleton agents

Rosenberg¹,

Sowers²

1994

Biophysical Journal

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We previously reported that the induction of membrane fusion between pairs of erythrocyte ghosts is accompanied by the formation of a multipore fusion zone that undergoes an area expansion with condition-dependent characteristics. These characteristics allowed us to hypothesize substantial, if not major, involvement of the spectrin-based membrane skeleton in controlling this expansion. It was also found that the fusion zone, which first appears in phase optics as a flat diaphragm, has a lifetime that is also highly condition-dependent. We report here that 2,3-diphosphoglycerate, wheat germ agglutinin, diamide, and N-ethylmaleimide, all known to have binding sites primarily on skeleton components (including spectrin), have condition-dependent effects on specific components of the fusion zone diameter versus time expansion curve and the flat diaphragm lifetime. We also report a pH/ionic strength condition that causes a dramatic stabilization of flat diaphragms in a manner consistent with the known pH/ionic strength dependence of the spectrin calorimetric transition, thus further supporting the hypothesis of spectrin involvement. Our data suggest that the influence of the membrane skeleton on cell fusion is to restrain the rounding up that takes place after membrane fusion and that it may have variable, rather than fixed, mechanical properties. Data show that WGA, a known ligand for sialic acid, and DPG, a known metabolite, influences the flat diaphragm stability and late period expansion rates, raising the possibility that some of these mechanical properties are biologically regulated.

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“…Different types of endogenous cellular membrane stimulus promote exovesiculation [2,3,4]. It was verified in vitro that changes in either pH or ATP, as well as the presence in incubation medium of amphiphilic compounds, induce the release of exovesicles from erythrocytes [5,6,7]. In these experimental conditions, the presence of the enzyme acetylcholinesterase (AChE) 11 is considered as a marker for the exovesiculation process [8,9].…”

Section: Introduction Introductionmentioning

confidence: 98%

Details of Laboratory Work for Medical Students

2021

bmms

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In the modern world of pandemics, a special place is occupied by the problems of education in the fi eld of medicine. In developed countries, medical education remains combined. Practical training of students in the laboratories of the uni-versity is very important. The article describes a biochemistry laboratory class protocol. This protocol is described in order to create an opportunity for students to apply by doing the theoretical concepts underlying biomolecules and vesicles proper-ties, together with the principles of centrifugation and colorimetric methodol-ogies. The aims, objectives, methodology of teaching/learning, and assessment for this laboratory class are indicated. The proposed protocol for a laboratory class described us creates the opportunity for undergraduate students to per-form experiments, to reason, and to discuss some related biochemical concepts, namely protein characterization and properties of specifi c staining reactions; en-zyme quantifi cation by enzymatic reaction; composition and biochemical prop-erties of exovesicles; amphiphilic biomolecules properties; and principles and applications of centrifugation methods. This work was supported by Portuguese Ministry of Science and Higher Education (MCES).

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Formation of large, membrane skeleton-free erythrocyte vesicles as a function of the intracellular pH and temperature

Cited by 13 publications

References 37 publications

Mechanism of intermembrane phosphatidylcholine transfer: Effects of pH and membrane configuration

Mechanism of intermembrane phosphatidylcholine transfer: Effects of pH and membrane configuration

Surface shape change during fusion of erythrocyte membranes is sensitive to membrane skeleton agents

Details of Laboratory Work for Medical Students

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