title: Involvement of VAT-1 in Phosphatidylserine Transfer from the Endoplasmic Reticulum to Mitochondria.
abstract: Mitochondria receive phosphatidylserine (PS) from the endoplasmic reticulum (ER), but how PS is moved from the ER to mitochondria is unclear. Current models postulate a physical link between the organelles, but no involvement of cytosolic proteins. Here, we have reconstituted PS transport from the ER to mitochondria in vitro using Xenopus egg components. Transport is independent of ER proteins, but is dependent on a cytosolic factor that has a preferential affinity for PS. Crosslinking with a photoactivatable PS analog identified VAT-1 as a candidate for a cytosolic PS transport protein. Recombinant, purified VAT-1 stimulated PS transport into mitochondria and depletion of VAT-1 from Xenopus cytosol with specific antibodies led to a reduction of transport. Our results suggest that cytosolic factors have a role in PS transport from the ER to mitochondria, implicate VAT-1 in the transport process, and indicate that physical contact between the organelles is not essential.
authors.affiliation: Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA, 02115, USA.
authors.forename: Mirco
authors.initials: M
authors.lastname: Junker
authors.affiliation: Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA, 02115, USA.
authors.forename: Tom A
authors.initials: TA
authors.lastname: Rapoport
mesh_terms: D000818:Animals; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D008081:Liposomes / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism*; D051336:Mitochondrial Membranes / Q000378:metabolism; D008954:Models, Biological; D010063:Ovum / Q000378:metabolism; D010718:Phosphatidylserines / Q000378:metabolism*; D021381:Protein Transport; D033921:Vesicular Transport Proteins / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis / Q000378:metabolism
chemical_list: D008081:Liposomes; D010718:Phosphatidylserines; C544158:VAT1 protein, human; D033921:Vesicular Transport Proteins
keywords: Xenopus leavis; endoplasmic reticulum; lipid transport; membrane; mitochondria; phosphatidylserine