A sequential model for peptide binding and transport by the transporters associated with antigen processing.
The TAP proteins translocate antigenic peptides into the endoplasmic reticulum. Investigation of the specificity of this process has been complicated by TAP-independent factors that influence the amount of peptide that accumulates in the ER in transport assays. We have developed an overexpression system in which binding of peptides to the TAP substrate-binding site and peptide transport by TAP can be quantified separately. Efficiency of peptide accumulation in the ER parallels affinity for the TAP substrate-binding site, but can be modified by interaction with the glycosylation system within the ER and, probably, peptide efflux. Random peptide mixtures of 9-16 aa display significantly higher affinity for the binding site than mixtures of shorter or longer peptides. Peptide binds to TAP heteromers in the absence of ATP and is released by the binding of ATP, suggesting a model for TAP function.
van Endert
P M
PM
Institut National de la Santé et de la Recherche Médicale U25, Paris, France.
Tampé
R
R
Meyer
T H
TH
Tisch
R
R
Bach
J F
JF
McDevitt
H O
HO
D000071181:ATP Binding Cassette Transporter, Subfamily B, Member 2; D000071450:ATP Binding Cassette Transporter, Subfamily B, Member 3; D018528:ATP-Binding Cassette Transporters / Q000096:biosynthesis / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D017951:Antigen Presentation / Q000276:immunology; D001665:Binding Sites; D001692:Biological Transport; D004721:Endoplasmic Reticulum / Q000378:metabolism; D015151:Immunoblotting; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D010455:Peptides / Q000378:metabolism*; D011233:Precipitin Tests; D011485:Protein Binding / Q000502:physiology; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000378:metabolism; D018411:Spodoptera
D000071181:ATP Binding Cassette Transporter, Subfamily B, Member 2; D000071450:ATP Binding Cassette Transporter, Subfamily B, Member 3; D018528:ATP-Binding Cassette Transporters; D010455:Peptides; D011994:Recombinant Proteins; C073119:TAP1 protein, human; C071692:TAP2 protein, human