6cay

Publication Abstract from PubMed

Lipid transport proteins at membrane contact sites, where two organelles are closely apposed, play key roles in trafficking lipids between cellular compartments while distinct membrane compositions for each organelle are maintained. Understanding the mechanisms underlying non-vesicular lipid trafficking requires characterization of the lipid transporters residing at contact sites. Here, we show that the mammalian proteins in the lipid transfer proteins anchored at a membrane contact site (LAM) family, called GRAMD1a-c, transfer sterols with similar efficiency as the yeast orthologues, which have known roles in sterol transport. Moreover, we have determined the structure of a lipid transfer domain of the yeast LAM protein Ysp2p, both in its apo-bound and sterol-bound forms, at 2.0 A resolution. It folds into a truncated version of the steroidogenic acute regulatory protein-related lipid transfer (StART) domain, resembling a lidded cup in overall shape. Ergosterol binds within the cup, with its 3-hydroxy group interacting with protein indirectly via a water network at the cup bottom. This ligand binding mode likely is conserved for the other LAM proteins and for StART domains transferring sterols.

Molecular basis for sterol transport by StART-like lipid transfer domains.,Horenkamp FA, Valverde DP, Nunnari J, Reinisch KM EMBO J. 2018 Feb 21. pii: embj.201798002. doi: 10.15252/embj.201798002. PMID:29467216^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.