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The quantity of naturally processed peptides stably bound by HLA-A*0201 is significantly reduced in the absence of tapasin

The quantity of naturally processed peptides stably bound by HLA-A*0201 is significantly reduced in the absence of tapasin
The quantity of naturally processed peptides stably bound by HLA-A*0201 is significantly reduced in the absence of tapasin
Tapasin plays a critical role in promoting peptide binding by major histocompatibility complex (MHC) class I molecules in the endoplasmic reticulum. In its absence, cell surface expression of most allotypes is significantly reduced. Two exceptions are HLA-A*0201 and HLA-B*2705. In this study, the repertoire of peptides bound endogenously by these allotypes in the absence of tapasin was examined and stability of the HLA class I/peptide complexes assessed. Similar quantities of peptides were recovered from B*2705 complexes expressed in the absence and presence of tapasin and the composition of the peptide pools were not radically different. However, the stability of B*2705 molecules expressed at the surface of tapasin-deficient cells was found to be reduced which suggests there are subtle changes to the peptide repertoire. The impact of the absence of tapasin was more dramatic for A*0201. Although equivalent levels of cell surface A*0201 are expressed in the presence and absence of tapasin, very little A*0201 glycoprotein was recovered from tapasin-deficient cells suggesting the complexes readily dissociate. Consistent with reduced stability, A*0201 complexes were found to be rapidly lost from the surface of tapasin-deficient cells. Analysis of the small quantity of endogenously bound peptides recovered from A*0201 expressed in the absence of tapasin revealed a complex mixture typical of A*0201 molecules expressed in normal cells. Therefore these molecules are unable to exploit the alternative supply of TAP-independent A*0201-binding peptides present in the endoplasmic reticulum. Loading of A*0201 with peptides from both TAP-dependent and TAP-independent sources is significantly compromised without tapasin.
0001-2815
363-368
Barber, L.D.
46dfed14-30a0-4871-92aa-baf7ce0dfa4e
Howarth, M.
3029a285-092c-4fae-8b03-d8c5d2dd73cc
Bowness, P.
2791367b-84e8-4d24-88f2-9f61a8b67556
Elliott, T.
16670fa8-c2f9-477a-91df-7c9e5b453e0e
Barber, L.D.
46dfed14-30a0-4871-92aa-baf7ce0dfa4e
Howarth, M.
3029a285-092c-4fae-8b03-d8c5d2dd73cc
Bowness, P.
2791367b-84e8-4d24-88f2-9f61a8b67556
Elliott, T.
16670fa8-c2f9-477a-91df-7c9e5b453e0e

Barber, L.D., Howarth, M., Bowness, P. and Elliott, T. (2001) The quantity of naturally processed peptides stably bound by HLA-A*0201 is significantly reduced in the absence of tapasin. Tissue Antigens, 58 (6), 363-368. (doi:10.1034/j.1399-0039.2001.580604.x).

Record type: Article

Abstract

Tapasin plays a critical role in promoting peptide binding by major histocompatibility complex (MHC) class I molecules in the endoplasmic reticulum. In its absence, cell surface expression of most allotypes is significantly reduced. Two exceptions are HLA-A*0201 and HLA-B*2705. In this study, the repertoire of peptides bound endogenously by these allotypes in the absence of tapasin was examined and stability of the HLA class I/peptide complexes assessed. Similar quantities of peptides were recovered from B*2705 complexes expressed in the absence and presence of tapasin and the composition of the peptide pools were not radically different. However, the stability of B*2705 molecules expressed at the surface of tapasin-deficient cells was found to be reduced which suggests there are subtle changes to the peptide repertoire. The impact of the absence of tapasin was more dramatic for A*0201. Although equivalent levels of cell surface A*0201 are expressed in the presence and absence of tapasin, very little A*0201 glycoprotein was recovered from tapasin-deficient cells suggesting the complexes readily dissociate. Consistent with reduced stability, A*0201 complexes were found to be rapidly lost from the surface of tapasin-deficient cells. Analysis of the small quantity of endogenously bound peptides recovered from A*0201 expressed in the absence of tapasin revealed a complex mixture typical of A*0201 molecules expressed in normal cells. Therefore these molecules are unable to exploit the alternative supply of TAP-independent A*0201-binding peptides present in the endoplasmic reticulum. Loading of A*0201 with peptides from both TAP-dependent and TAP-independent sources is significantly compromised without tapasin.

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Published date: 2001

Identifiers

Local EPrints ID: 26211
URI: http://eprints.soton.ac.uk/id/eprint/26211
ISSN: 0001-2815
PURE UUID: e2fefdfe-316b-4abb-a318-f34180eda821
ORCID for T. Elliott: ORCID iD orcid.org/0000-0003-1097-0222

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Date deposited: 24 Apr 2006
Last modified: 16 Mar 2024 03:19

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Contributors

Author: L.D. Barber
Author: M. Howarth
Author: P. Bowness
Author: T. Elliott ORCID iD

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