title: Identification of a lipid scrambling domain in ANO6/TMEM16F.
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.
authors.affiliation: Department of Cell Biology, Emory University School of Medicine, Atlanta, United States.
authors.forename: Kuai
authors.initials: K
authors.lastname: Yu
authors.affiliation: Department of Cell Biology, Emory University School of Medicine, Atlanta, United States.
authors.forename: Jarred M
authors.identifier: http://orcid.org/0000-0002-5886-2047
authors.initials: JM
authors.lastname: Whitlock
authors.affiliation: Department of Cell Biology, Emory University School of Medicine, Atlanta, United States.
authors.forename: Kyleen
authors.identifier: http://orcid.org/0000-0003-2418-226X
authors.initials: K
authors.lastname: Lee
authors.affiliation: Department of Cell Biology, Emory University School of Medicine, Atlanta, United States.
authors.forename: Eric A
authors.initials: EA
authors.lastname: Ortlund
authors.affiliation: Department of Cell Biology, Emory University School of Medicine, Atlanta, United States.
authors.forename: Yuan Yuan
authors.initials: YY
authors.lastname: Cui
authors.affiliation: Department of Cell Biology, Emory University School of Medicine, Atlanta, United States.
authors.forename: H Criss
authors.identifier: http://orcid.org/0000-0002-3393-1528
authors.initials: HC
authors.lastname: Hartzell
mesh_terms: D000075368:Anoctamins; D002462:Cell Membrane / Q000378:metabolism*; D002478:Cells, Cultured; D004252:DNA Mutational Analysis; D006801:Humans; D018408:Patch-Clamp Techniques; D049294:Phospholipid Transfer Proteins / Q000235:genetics / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism*; D011487:Protein Conformation; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: C555078:ANO6 protein, human; D000075368:Anoctamins; D049294:Phospholipid Transfer Proteins; D010743:Phospholipids; D011993:Recombinant Fusion Proteins
keywords: anion channel; biophysics; cell biology; chloride channel; human; membrane channels; membrane transport; mouse; phospholipids; structural biology