A point mutation in the human transporter associated with antigen processing (TAP2) alters the peptide transport specificity

Elena A. Armandola, Frank Momburg, Marga Nijenhuis, Nadja Bulbuc, Klaus Frueh, Günter J. Hämmerling

Research output: Contribution to journalArticle

70 Citations (Scopus)

Abstract

The heterodimeric transporter associated with antigen processing (TAP1/TAP2) translocates peptides from the cytosol into the endoplasmic reticulum where loading of major histocompatibility complex class I molecules takes place. TAP transporters from different species are known to exhibit distinct transport specificities with regard to the C-terminal amino acid (aa) of peptides. Thus, human TAP (hTAP), and rat TAP (rTAP) containing the rTAP2(u) allele are rather promiscuous, whereas mouse TAP (mTAP), and rTAP containing the rTAP2(u) allele are restrictive and select against peptides with C-terminal small polar/hydrophobic or positively charged aa. The structural basis for this selectivity is not clear. To assess the relative contribution of the TAP1 and TAP2 subunits to transport specificity, we have constructed and analyzed interspecies TAP hybrids and point mutants of hTAP2 expressed in Sf9 insect cells and in TAP-deficient T2 cells. Transport assays with 20 C-terminal variants of the peptide RYWA-NATRSX showed that: first, transport specificity with regard to C-terminal aa is mainly influenced by TAP2, but TAP1 can also contribute. Second, the selective transport of peptides with C-terminal positively charged aa is critically controlled by the amino-terminal region (1-361) on the TAP2 chain, while transport of peptides with C-terminal small polar/hydrophobic aa is determined by residues located within as well as outside the region 1-361. Third, a single point mutation in hTAP2 (374A → D) resulted in a drastic alteration of the transport pattern. These results indicate that both TAP1 and TAP2 contribute to efficient peptide transport and that single point mutations in hTAP2 are able to alter the peptide transport specificity. This opens the possibility that naturally occurring mutations in one of the hTAP subunits may alter epitope selection in vivo.

Original languageEnglish (US)
Pages (from-to)1748-1755
Number of pages8
JournalEuropean Journal of Immunology
Volume26
Issue number8
StatePublished - 1996
Externally publishedYes

Fingerprint

Antigen Presentation
Point Mutation
Amino Acids
Peptides
Alleles
Sf9 Cells
Major Histocompatibility Complex
Endoplasmic Reticulum
Cytosol
Insects
Epitopes
Mutation
polypeptide C

Keywords

  • Antigen processing
  • Major histocompatibility complex
  • TAP peptide
  • Transport

ASJC Scopus subject areas

  • Immunology

Cite this

A point mutation in the human transporter associated with antigen processing (TAP2) alters the peptide transport specificity. / Armandola, Elena A.; Momburg, Frank; Nijenhuis, Marga; Bulbuc, Nadja; Frueh, Klaus; Hämmerling, Günter J.

In: European Journal of Immunology, Vol. 26, No. 8, 1996, p. 1748-1755.

Research output: Contribution to journalArticle

Armandola, EA, Momburg, F, Nijenhuis, M, Bulbuc, N, Frueh, K & Hämmerling, GJ 1996, 'A point mutation in the human transporter associated with antigen processing (TAP2) alters the peptide transport specificity', European Journal of Immunology, vol. 26, no. 8, pp. 1748-1755.
Armandola, Elena A. ; Momburg, Frank ; Nijenhuis, Marga ; Bulbuc, Nadja ; Frueh, Klaus ; Hämmerling, Günter J. / A point mutation in the human transporter associated with antigen processing (TAP2) alters the peptide transport specificity. In: European Journal of Immunology. 1996 ; Vol. 26, No. 8. pp. 1748-1755.
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AU - Armandola, Elena A.

AU - Momburg, Frank

AU - Nijenhuis, Marga

AU - Bulbuc, Nadja

AU - Frueh, Klaus

AU - Hämmerling, Günter J.

PY - 1996

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AB - The heterodimeric transporter associated with antigen processing (TAP1/TAP2) translocates peptides from the cytosol into the endoplasmic reticulum where loading of major histocompatibility complex class I molecules takes place. TAP transporters from different species are known to exhibit distinct transport specificities with regard to the C-terminal amino acid (aa) of peptides. Thus, human TAP (hTAP), and rat TAP (rTAP) containing the rTAP2(u) allele are rather promiscuous, whereas mouse TAP (mTAP), and rTAP containing the rTAP2(u) allele are restrictive and select against peptides with C-terminal small polar/hydrophobic or positively charged aa. The structural basis for this selectivity is not clear. To assess the relative contribution of the TAP1 and TAP2 subunits to transport specificity, we have constructed and analyzed interspecies TAP hybrids and point mutants of hTAP2 expressed in Sf9 insect cells and in TAP-deficient T2 cells. Transport assays with 20 C-terminal variants of the peptide RYWA-NATRSX showed that: first, transport specificity with regard to C-terminal aa is mainly influenced by TAP2, but TAP1 can also contribute. Second, the selective transport of peptides with C-terminal positively charged aa is critically controlled by the amino-terminal region (1-361) on the TAP2 chain, while transport of peptides with C-terminal small polar/hydrophobic aa is determined by residues located within as well as outside the region 1-361. Third, a single point mutation in hTAP2 (374A → D) resulted in a drastic alteration of the transport pattern. These results indicate that both TAP1 and TAP2 contribute to efficient peptide transport and that single point mutations in hTAP2 are able to alter the peptide transport specificity. This opens the possibility that naturally occurring mutations in one of the hTAP subunits may alter epitope selection in vivo.

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KW - Transport

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