Protein Crowding Is a Determinant of Lipid Droplet Protein Composition.

Dev Cell
Authors
Keywords
Abstract

Lipid droplets (LDs) are lipid storage organelles that grow or shrink, depending on the availability of metabolic energy. Proteins recruited to LDs mediate many metabolic functions, including phosphatidylcholine and triglyceride synthesis. How the LD protein composition is tuned to the supply and demand for lipids remains unclear. We show that LDs, in contrast to other organelles, have limited capacity for protein binding. Consequently, macromolecular crowding plays a major role in determining LD protein composition. During lipolysis, when LDs and their surfaces shrink, some, but not all, proteins become displaced. In vitro studies show that macromolecular crowding, rather than changes in monolayer lipid composition, causes proteins to fall off the LD surface. As predicted by a crowding model, proteins compete for binding to the surfaces of LDs. Moreover, the LD binding affinity determines protein localization during lipolysis. Our findings identify protein crowding as an important principle in determining LD protein composition.

Year of Publication
2015
Journal
Dev Cell
Volume
34
Issue
3
Pages
351-63
Date Published
2015 Aug 10
ISSN
1878-1551
URL
DOI
10.1016/j.devcel.2015.06.007
PubMed ID
26212136
PubMed Central ID
PMC4536137
Links
Grant list
R01 GM097194 / GM / NIGMS NIH HHS / United States
R01 GM095982 / GM / NIGMS NIH HHS / United States
R01GM-099844 / GM / NIGMS NIH HHS / United States
R01GM-097194 / GM / NIGMS NIH HHS / United States
R01 GM099844 / GM / NIGMS NIH HHS / United States