Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 1990 Feb 27;29(8):2023-7.
doi: 10.1021/bi00460a010.

Protein-mediated phospholipid translocation in the endoplasmic reticulum with a low lipid specificity

A Herrmann  1 , A Zachowski, P F Devaux
Affiliations

Protein-mediated phospholipid translocation in the endoplasmic reticulum with a low lipid specificity

A Herrmann et al. Biochemistry. .

Abstract

The outside-inside translocation rate of various amphiphilic spin-labeled phospholipids has been measured in rat liver endoplasmic reticulum vesicles. The eight spin-labels tested experienced a fast flip-flop rate with the same half-time of approximately 20 min at 37 degrees C. The stationary distribution of these phospholipid analogues was ca. 45% on the inner vesicular leaflet and 55% on the external one, showing that there is no net enrichment of some lipid in one layer under the experimental conditions used. The initial rate of translocation was reduced 4-fold if membranes were preincubated with N-ethylmaleimide (2 mM) and was about an order of magnitude lower in liposomes made from the extracted lipids. An apparent saturability of the transbilayer diffusion can be deduced from the variation of the initial velocity of the relocation kinetics vs the amount of analogue incorporated in the membrane. Moreover, translocation rates of two different spin-labeled phospholipids introduced simultaneously in the membrane were almost equally reduced by the presence of the other lipid. On the other hand, no competition between the water-soluble dibutyroylphosphatidylcholine and the amphiphilic spin-labeled phospholipids could be detected. Overall, these results suggest that phospholipid translocation in the endoplasmic reticulum is a protein-mediated process with a low specificity, which tends, in the absence of any other metabolic event, to equilibrate the phospholipid composition of the two membrane halves.

PubMed Disclaimer

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

Publication types