Phospholipid asymmetry in large unilamellar vesicles induced by transmembrane pH gradients

Journal Article · Tue May 16 00:00:00 EDT 1989 · Biochemistry; (USA)

DOI:https://doi.org/10.1021/bi00436a009· OSTI ID:5353669

Hope, M J; Redelmeier, T E; Wong, K F; Rodrigueza, W; Cullis, P R ^[1]

---

1. Univ. of British Columbia, Vancouver (Canada)

The influence of membrane pH gradients on the transbilayer distribution of some common phospholipids has been investigated. The authors demonstrate that the transbilayer equilibrium of the acidic phospholipids egg phosphatidylglycerol (EPG) and egg phosphatidic acid (EPA) can be manipulated by membrane proton gradients, whereas phosphatidylethanolamine, a zwitterionic phospholipid, remains equally distributed between the inner and outer monolayers of large unilamellar vesicles (LUVs). Asymmetry of EPG is examined in detail and demonstrated by employing three independent techniques: ion-exchange chromatography, {sup 13}C NMR, and periodic acid oxidation of the (exterior) EPG headgroup. In the absence of a transmembrane pH gradient ({Delta}pH) EPG is equally distributed between the outer and inner monolayers of LuVs. When vesicles composed of either egg phosphatidylcholine (EPC) or DOPC together with 5 mol % EPG are prepared with a transmembrane {Delta}pH. EPG equilibrates across the bilayer until 80-90% of the EPG is located in the inner monolayer. Reversing the pH gradient results in the opposite asymmetry. The rate at which EPG equilibrates across the membrane is temperature dependent. These observations are consistent with a mechanism in which the protonated (neutral) species of EPG is able to traverse the bilayer. Under these circumstances EPG would be expected to equilibrate across the bilayer in a manner that reflects the transmembrane proton gradient.

• OSTI ID: 5353669
• Journal Information: Biochemistry; (USA), Journal Name: Biochemistry; (USA) Vol. 28:10; ISSN 0006-2960; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ASYMMETRY
BIOCHEMICAL REACTION KINETICS
CARBON 13
CARBON ISOTOPES
CELL CONSTITUENTS
CELL MEMBRANES
CHARGED PARTICLES
ESTERS
EVEN-ODD NUCLEI
IONS
ISOTOPES
KINETICS
LIGHT NUCLEI
LIPIDS
MAGNETIC RESONANCE
MEMBRANE TRANSPORT
MEMBRANES
NUCLEAR MAGNETIC RESONANCE
NUCLEI
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
PH VALUE
PHOSPHOLIPIDS
REACTION KINETICS
RESONANCE
STABLE ISOTOPES