Lateral diffusion of GFP-tagged H2Ld molecules and of GFP-TAP1 reports on the assembly and retention of these molecules in the endoplasmic reticulum.
Lateral diffusion of GFP-tagged H2Ld molecules in the ER membrane reports on their interaction with the TAP complex during synthesis and peptide loading. Peptide-loaded H2Ld molecules diffuse rapidly, near the theoretical limit for proteins in a bilayer. However, these molecules are retained in the ER for some time after assembly. H2Ld molecules, associated with the TAP complex, diffuse slowly, as does GFP-tagged TAP1. This implies that the association of H2Ld molecules with the TAP complex is stable for at least several minutes. It also suggests that the TAP complex is very large, perhaps containing hundreds of proteins.
Marguet
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Department of Biology, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
Spiliotis
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Pentcheva
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Lebowitz
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Schneck
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Edidin
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D000071181:ATP Binding Cassette Transporter, Subfamily B, Member 2; D018528:ATP-Binding Cassette Transporters / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D004058:Diffusion; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D049452:Green Fluorescent Proteins; D006183:H-2 Antigens / Q000737:chemistry / Q000378:metabolism*; D064532:Histocompatibility Antigen H-2D; D008164:Luminescent Proteins / Q000737:chemistry / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D011993:Recombinant Fusion Proteins / Q000378:metabolism*
D000071181:ATP Binding Cassette Transporter, Subfamily B, Member 2; D018528:ATP-Binding Cassette Transporters; D006183:H-2 Antigens; D064532:Histocompatibility Antigen H-2D; D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; C073119:TAP1 protein, human; C486171:Tap1 protein, mouse; D049452:Green Fluorescent Proteins