7RSL image
Deposition Date 2021-08-11
Release Date 2022-02-09
Last Version Date 2024-06-05
Entry Detail
PDB ID:
7RSL
Title:
Seipin forms a flexible cage at lipid droplet formation sites
Biological Source:
Source Organism:
Method Details:
Experimental Method:
Resolution:
3.45 Å
Aggregation State:
PARTICLE
Reconstruction Method:
SINGLE PARTICLE
Macromolecular Entities
Polymer Type:polypeptide(L)
Molecule:Seipin
Gene (Uniprot):SEI1
Chain IDs:A, B, C (auth: G), D (auth: H), E, F, G (auth: I), H (auth: J), I (auth: C), J (auth: D)
Chain Length:285
Number of Molecules:10
Biological Source:Saccharomyces cerevisiae
Ligand Molecules
Primary Citation
Seipin forms a flexible cage at lipid droplet formation sites.
Nat.Struct.Mol.Biol. 29 194 202 (2022)
PMID: 35210614 DOI: 10.1038/s41594-021-00718-y

Abstact

Lipid droplets (LDs) form in the endoplasmic reticulum by phase separation of neutral lipids. This process is facilitated by the seipin protein complex, which consists of a ring of seipin monomers, with a yet unclear function. Here, we report a structure of S. cerevisiae seipin based on cryogenic-electron microscopy and structural modeling data. Seipin forms a decameric, cage-like structure with the lumenal domains forming a stable ring at the cage floor and transmembrane segments forming the cage sides and top. The transmembrane segments interact with adjacent monomers in two distinct, alternating conformations. These conformations result from changes in switch regions, located between the lumenal domains and the transmembrane segments, that are required for seipin function. Our data indicate a model for LD formation in which a closed seipin cage enables triacylglycerol phase separation and subsequently switches to an open conformation to allow LD growth and budding.

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