In or out of the groove? Mechanisms of lipid scrambling by TMEM16 proteins.
Cell Calcium
; 121: 102896, 2024 Jul.
Article
in En
| MEDLINE
| ID: mdl-38749289
ABSTRACT
Phospholipid scramblases mediate the rapid movement of lipids between membrane leaflets, a key step in establishing and maintaining membrane homeostasis of the membranes of all eukaryotic cells and their organelles. Thus, impairment of lipid scrambling can lead to a variety of pathologies. How scramblases catalyzed the transbilayer movement of lipids remains poorly understood. Despite the availability of direct structural information on three unrelated families of scramblases, the TMEM16s, the Xkrs, and ATG-9, a unifying mechanism has failed to emerge thus far. Among these, the most extensively studied and best understood are the Ca2+ activated TMEM16s, which comprise ion channels and/or scramblases. Early work supported the view that these proteins provided a hydrophilic, membrane-exposed groove through which the lipid headgroups could permeate. However, structural, and functional experiments have since challenged this mechanism, leading to the proposal that the TMEM16s distort and thin the membrane near the groove to facilitate lipid scrambling. Here, we review our understanding of the structural and mechanistic underpinnings of lipid scrambling by the TMEM16s and discuss how the different proposals account for the various experimental observations.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Phospholipid Transfer Proteins
/
Anoctamins
Limits:
Animals
/
Humans
Language:
En
Journal:
Cell Calcium
Year:
2024
Document type:
Article
Affiliation country: