title: Specific lipids modulate the transporter associated with antigen processing (TAP).
abstract: The transporter associated with antigen processing (TAP) plays a key role in adaptive immunity by translocating proteasomal degradation products from the cytosol into the endoplasmic reticulum lumen for subsequent loading onto major histocompatibility (MHC) class I molecules. For functional and structural analysis of this ATP-binding cassette complex, we established the overexpression of TAP in the methylotrophic yeast Pichia pastoris. Screening of optimal solubilization and purification conditions allowed the isolation of the heterodimeric transport complex, yielding 30 mg of TAP/liter of culture. Detailed analysis of TAP function in the membrane, solubilized, purified, and reconstituted states revealed a direct influence of the native lipid environment on activity. TAP-associated phospholipids, essential for function, were profiled by liquid chromatography Fourier transform mass spectrometry. The antigen translocation activity is stimulated by phosphatidylinositol and -ethanolamine, whereas cholesterol has a negative effect on TAP activity.
authors.affiliation: Institute of Biochemistry, Biocenter, Goethe-University Frankfurt, Max-von-Laue Strasse 9, D-60438 Frankfurt am Main, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Schölz
authors.forename: David
authors.initials: D
authors.lastname: Parcej
authors.forename: Christer S
authors.initials: CS
authors.lastname: Ejsing
authors.forename: Horst
authors.initials: H
authors.lastname: Robenek
authors.forename: Ina L
authors.initials: IL
authors.lastname: Urbatsch
authors.forename: Robert
authors.initials: R
authors.lastname: Tampé
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000737:chemistry* / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D006801:Humans; D008563:Membrane Lipids / Q000737:chemistry* / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D010843:Pichia / Q000235:genetics; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism
chemical_list: D018528:ATP-Binding Cassette Transporters; D008563:Membrane Lipids; D011994:Recombinant Proteins; C477327:transporter associated with antigen processing (TAP)