期刊
BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH
卷 1773, 期 6, 页码 784-793出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.bbamcr.2007.02.004
关键词
membrane traffic; endosome; rabs; adiposomes; lipid droplets
资金
- NHLBI NIH HHS [P01 HL020948, HL20948, P01 HL020948-260020] Funding Source: Medline
- NIGMS NIH HHS [F32 GM070117, R01 GM052016, GM70117, R01 GM052016-12, GM52016] Funding Source: Medline
Recent studies indicate that lipid droplets isolated from a variety of different cells are rich in proteins known to regulate membrane traffic. Among these proteins are multiple Rab GTPases. Rabs are GTP switches that regulate intracellular membrane traffic through an ability to control membrane-membrane docking as well as vesicle motility. Here we present evidence that the multiple Rabs associated with droplets have a function in regulating membrane traffic. Droplet Rabs are removed by Rab GDP-dissociation inhibitor (RabGDI) in a GDP-dependent reaction, and are recruited to Rab-depleted droplets from cytosol in a GTP-dependent reaction. Rabs also control the recruitment of the early endosome (EE) marker EEA I from cytosol. We use an in vitro reconstitution assay to show that transferrin receptor positive EEs bind to the droplet in a GTP/Rabdependent reaction that appears not to lead to membrane fusion. This docking reaction is insensitive to ATP(gamma S) but is blocked by ATP. Finally, we show that when GTP bound active or GDP bound inactive Rab5 is targeted to the droplet, the active form recruits EEA1 We conclude that the Rabs associated with droplets may be capable of regulating the transient interaction of specific membrane systems, probably to transport lipids between membrane compartments. Published by Elsevier B.V.
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