Membrane contact sites are structures where two organelles come close together to regulate flow of material and information between them. One type of inter-organelle communication is lipid exchange, which must occur for membrane maintenance and in response to environmental and cellular stimuli. Soluble lipid transfer proteins have been extensively studied, but additional families of transfer proteins have been identified that are anchored into membranes by transmembrane helices so that they cannot diffuse through the cytosol to deliver lipids. If such proteins target membrane contact sites they may be major players in lipid metabolism. The eukaryotic family of so-called Lipid transfer proteins Anchored at Membrane contact sites (LAMs) all contain both a sterol-specific lipid transfer domain in the StARkin superfamily (related to StART/Bet_v1), and one or more transmembrane helices anchoring them in the endoplasmic reticulum (ER), making them interesting subjects for study in relation to sterol metabolism. They target a variety of membrane contact sites, including newly described contacts between organelles that were already known to make contact by other means. Lam1–4p target punctate ER–plasma membrane contacts. Lam5p and Lam6p target multiple contacts including a new category: vacuolar non-NVJ cytoplasmic ER (VancE) contacts. These developments confirm previous observations on tubular lipid-binding proteins (TULIPs) that established the importance of membrane anchored proteins for lipid traffic. However, the question remaining to be solved is the most difficult of all: are LAMs transporters, or alternately are they regulators that affect traffic more indirectly?
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April 2016
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Cover Image
Endoplasmic reticulumendosome contact sites. This pseudo-colored electron microscopy image shows the formation of inter-organelle membrane contact sites between late endosomes (magenta) and the endoplasmic reticulum (ER; green). This tethering results from the interaction between two ER-anchored proteins (VAP-A and VAP-B) and the late endosomeanchored protein STARD3NL. Mitochondria: brown; nucleus: blue. For further details see pp. 493-498. Image kindly provided by Fabien Alpy. - PDF Icon PDF LinkTable of Contents
Review Article|
April 11 2016
Lipid transfer proteins do their thing anchored at membrane contact sites… but what is their thing?
Louise H. Wong;
Louise H. Wong
*Department of Cell Biology, UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, U.K.
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Tim P. Levine
Tim P. Levine
1
*Department of Cell Biology, UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, U.K.
1To whom correspondence should be addressed (email tim.levine@ucl.ac.uk).
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Publisher: Portland Press Ltd
Received:
February 09 2016
Online ISSN: 1470-8752
Print ISSN: 0300-5127
© 2016 Authors; published by Portland Press Limited
2016
Biochem Soc Trans (2016) 44 (2): 517–527.
Article history
Received:
February 09 2016
Citation
Louise H. Wong, Tim P. Levine; Lipid transfer proteins do their thing anchored at membrane contact sites… but what is their thing?. Biochem Soc Trans 15 April 2016; 44 (2): 517–527. doi: https://doi.org/10.1042/BST20150275
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