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Interactions formed by individually expressed TAP1 and TAP2 polypeptide subunits.

Authors: Antoniou, AN  Ford, S  Pilley, ES  Blake, N  Powis, SJ 
Citation: Antoniou AN, etal., Immunology. 2002 Jun;106(2):182-9.
Pubmed: (View Article at PubMed) PMID:12047747

The transporter associated with antigen processing (TAP) supplies peptides into the lumen of the endoplasmic reticulum (ER) for binding by major histocompatibility complex (MHC) class I molecules. TAP comprises two polypeptides, TAP1 and TAP2, each a 'half-transporter' encoding a transmembrane domain and a nucleotide-binding domain. Immunoprecipitation of rat TAP1 and TAP2 expressed individually in the human TAP-deficient cell line, T2, revealed that both bound the endogenously expressed HLA-A2 and -B51 class I molecules. Using HLA-encoding recombinant vaccinia viruses HLA-A*2501, -B*2704, -B*3501 and -B*4402, alleles also associated with both TAP1 and TAP2. Thus, TAP1 and TAP2 do not appear to differ in their ability to interact with MHC class I alleles. Single TAP polypeptide subunits also formed MHC class I peptide-loading complexes, and their nucleotide-binding domains retained the ability to interact with ATP, and may permit the release of peptide-loaded MHC class I molecules in the absence of a peptide transport cycle. It is also demonstrated by chemical cross-linking that TAP2, but not TAP1, has the ability to form a homodimer complex both in whole cells and in detergent lysates. Together these data indicate that single TAP polypeptide subunits possess many of the features of the TAP heterodimer, demonstrating them to be useful models in the study of ATP-binding cassette (ABC) transporters.


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RGD Object Information
RGD ID: 5147838
Created: 2011-08-23
Species: All species
Last Modified: 2011-08-23
Status: ACTIVE


RGD is funded by grant HL64541 from the National Heart, Lung, and Blood Institute on behalf of the NIH.