Identification of a lipid scrambling domain in ANO6/TMEM16F.

• Type of Material: Article
• Authors: Kuai Yu, Emory University; Jarred M Whitlock, Emory University; Kyleen Lee, Emory University; Eric Ortlund, Emory University; Yuan Yuan Cui, Emory University; Harrison Hartzell Jr., Emory University
• Language: English
• Date: 2015
• Publisher: eLife Sciences Publications
• Publication Version: Final Published Version
• Copyright Statement: © 2015, Yu et al
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.7554/eLife.06901
• Title of Journal or Parent Work: eLife
• ISSN: 2050-084X
• Volume: 4
• Grant/Funding Information: Supported by NIH grants GM60448-12 and EY114852-11 to HCH.; This research project was supported in part by the Emory University Integrated Cellular Imaging Microscopy Core.; Jarred Whitlock was supported by an NIH Training Grant 5T32GM008367-25.
• Research Categories: Biology, Cell; Chemistry, Biochemistry

Abstract

Phospholipid scrambling (PLS) is a ubiquitous cellular mechanism involving the regulated bidirectional transport of phospholipids down their concentration gradient between membrane leaflets. ANO6/TMEM16F has been shown to be essential for Ca(2+)-dependent PLS, but controversy surrounds whether ANO6 is a phospholipid scramblase or an ion channel like other ANO/TMEM16 family members. Combining patch clamp recording with measurement of PLS, we show that ANO6 elicits robust Ca(2+)-dependent PLS coinciding with ionic currents that are explained by ionic leak during phospholipid translocation. By analyzing ANO1-ANO6 chimeric proteins, we identify a domain in ANO6 necessary for PLS and sufficient to confer this function on ANO1, which normally does not scramble. Homology modeling shows that the scramblase domain forms an unusual hydrophilic cleft that faces the lipid bilayer and may function to facilitate translocation of phospholipid between membrane leaflets. These findings provide a mechanistic framework for understanding PLS and how ANO6 functions in this process.