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09:52
A Fluorescence-based Assay of Phospholipid Scramblase Activity
Published on: September 20, 2016
ATP8A1 activity and phosphatidylserine transbilayer movement
Eric Soupene1, Dwi Utami Kemaladewi, Frans A Kuypers
1Children's Hospital Oakland Research Institute, Oakland, CA, USA.
Journal of Receptor, Ligand and Channel Research
|March 13, 2010
Summary
Researchers identified the Atp8a1 protein as a red blood cell (RBC) flippase, crucial for maintaining cell membrane asymmetry. This discovery sheds light on RBC disorders and hemoglobinopathies by identifying a key protein involved in phospholipid transport.
Area of Science:
- Membrane Biology
- Biochemistry
- Cellular Physiology
Background:
- Asymmetric distribution of amino-phospholipids (phosphatidyl-serine and phosphatidyl-ethanolamine) is vital for red blood cell (RBC) function.
- RBC flippase activity maintains this asymmetry, but its inactivation leads to PS exposure, exacerbating RBC disorders and hemoglobinopathies.
Purpose of the Study:
- To identify the RBC flippase responsible for maintaining phospholipid asymmetry.
- To investigate the role of the P(4)-ATPase family member, Atp8a1, as a candidate RBC flippase.
Main Methods:
- Investigated Atp8a1 expression in RBC precursors and mature RBC membranes.
- Assessed Atp8a1 flippase activity using purified secretory vesicles from Saccharomyces cerevisiae.
- Measured ATPase activity in the presence of phosphatidyl-serine (PS) and phosphatidyl-ethanolamine (PE).
Main Results:
- Atp8a1 is expressed in RBC precursors and present in mature RBC membranes.
- Purified secretory vesicles expressing Atp8a1 demonstrated flippase activity.
- Atp8a1's ATPase activity was stimulated by PS and PE, and it facilitated PS transport across vesicle membranes.
Conclusions:
- The P(4)-ATPase Atp8a1 functions as the RBC flippase.
- Atp8a1 plays a critical role in maintaining red blood cell membrane phospholipid asymmetry.
- Understanding Atp8a1's function is key to addressing pathologies in RBC disorders and hemoglobinopathies.
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