• Nanion Technologies: イオンチャネル研究のスマートツール

    Nanion Technologies: イオンチャネル研究のスマートツール

  • SyncroPatch 384i: HTS Automated Patch Clamp

    SyncroPatch 384i: HTS Automated Patch Clamp

  • SURFE²R 96SE: ラベルフリーのトランスポーターHTS

    SURFE²R 96SE: ラベルフリーのトランスポーターHTS

  • Dynamic Clamp: Patchliner

    Dynamic Clamp: Patchliner

  • 脂質二分子膜実験: Orbitシリーズ

    脂質二分子膜実験: Orbitシリーズ

  • CardioExcyte 96 SOL: 心筋の光ペーシング

    CardioExcyte 96 SOL: 心筋の光ペーシング

Our Product Portfolio

SyncroPatch 384i

SyncroPatch 384i

Patchliner

Patchliner

Port-a-Patch

Port-a-Patch

Port-a-Patch mini

Port-a-Patch mini

CardioExcyte 96

CardioExcyte 96

FLEXcyte 96

FLEXcyte 96

SURFE²R 96SE

SURFE²R 96SE

SURFE²R N1

SURFE²R N1

Orbit 16

Orbit 16

Orbit Mini

Orbit Mini

Vesicle Prep Pro

Vesicle Prep Pro

2019 - Phosphatidylserine flipping by the P4-ATPase ATP8A2 is electrogenic

Icon N1   SURFE²R ONE (a predecessor model of SURFE²R N1) publication in PNAS (2019)

Authors:
Tadini-Buoninsegni F., Mikkelsen S.A., Mogensen L.S., Molday R.S., and Andersen J.P.

Journal:
PNAS (2019) 116(33): 16332-16337


Significance

Phospholipid flippases constitute the largest subfamily of P-type ATPases and have in eukaryotic organisms evolved as a central transport system for selective translocation of phospholipids across biological membranes to generate membrane lipid asymmetry, a property essential for numerous cellular processes. The importance of flippases is highlighted by severe neurological disorders and liver diseases caused by flippase dysfunction in humans. The electrogenicity of phospholipid transport by flippases has not previously been explored. We demonstrated that phosphatidylserine translocation by the flippase ATP8A2 generates electrical current, resulting from specific steps in the flippase reaction cycle moving the charged lipid head group between the membrane bilayer leaflets, and that no charged substrate is being countertransported. These findings unravel key features of phospholipid flippases.

Abstract

Phospholipid flippases (P4-ATPases) utilize ATP to translocate specific phospholipids from the exoplasmic leaflet to the cytoplasmic leaflet of biological membranes, thus generating and maintaining transmembrane lipid asymmetry essential for a variety of cellular processes. P4-ATPases belong to the P-type ATPase protein family, which also encompasses the ion transporting P2-ATPases: Ca2+-ATPase, Na+,K+-ATPase, and H+,K+-ATPase. In comparison with the P2-ATPases, understanding of P4-ATPases is still very limited. The electrogenicity of P4-ATPases has not been explored, and it is not known whether lipid transfer between membrane bilayer leaflets can lead to displacement of charge across the membrane. A related question is whether P4-ATPases countertransport ions or other substrates in the opposite direction, similar to the P2-ATPases. Using an electrophysiological method based on solid supported membranes, we observed the generation of a transient electrical current by the mammalian P4-ATPase ATP8A2 in the presence of ATP and the negatively charged lipid substrate phosphatidylserine, whereas only a diminutive current was generated with the lipid substrate phosphatidylethanolamine, which carries no or little charge under the conditions of the measurement. The current transient seen with phosphatidylserine was abolished by the mutation E198Q, which blocks dephosphorylation. Likewise, mutation I364M, which causes the neurological disorder cerebellar ataxia, mental retardation, and disequilibrium (CAMRQ) syndrome, strongly interfered with the electrogenic lipid translocation. It is concluded that the electrogenicity is associated with a step in the ATPase reaction cycle directly involved in translocation of the lipid. These measurements also showed that no charged substrate is being countertransported, thereby distinguishing the P4-ATPase from P2-ATPases.


Download here

Back

Nanion コーポレートブログ

We use cookies on our website. Some of them are essential for the operation of the site, while others help us to improve this site and the user experience (tracking cookies). You can decide for yourself whether you want to allow cookies or not. Please note that if you reject them, you may not be able to use all the functionalities of the site.