Requirements for HLA-B*2705-binding peptides with special regard to the transporter associated with antigen processing (TAP).
OBJECTIVE
To refine the algorithms governing peptide presentation by HLA-B*2705 by analyzing: (i) the specificity of the human transporter associated with antigen processing (TAP) for HLA-B27 binding peptides; and (ii) the peptide binding affinity to HLA-B*2705.


METHODS
TAP-translocation was measured with a labeled reporter peptide containing an N-linked glycosylation acceptor site in Streptolysin O-permeabilized cells for a panel of HLA-B27 binding peptides. Peptide binding affinity was determined by peptide-induced stabilization of empty HLA-B*2705 expressed by the TAP-deficient cell line T2-B27.


RESULTS
Human TAP preferentially translocated analogues with residues leucine, isoleucine, methionine and arginine as the carboxy-terminal amino acids, whereas analogues with aspartic acid and serine were translocated poorly. The binding affinity to HLA-B*2705 of the poorly translocated aspartic acid and serine analogues was about 100-fold less compared to the parent HLA-B27 binding peptide.


CONCLUSIONS
Human TAP shows considerable specificity for the C-terminus of potential HLA-B27 ligands. Nonamer peptides with aspartic acid and serine at the C-terminus are poorly translocated by the TAP and have low binding affinity for HLA-B*2705, and are therefore unlikely to become presented by HLA-B*2705.
Abteilung Rheumatologie, Medizinische Hochschule, Hannover, Germany.
J G
JG
Kuipers
R
R
Raybourne
K M
KM
Williams
H
H
Zeidler
D T
DT
Yu
D018528:ATP-Binding Cassette Transporters / Q000276:immunology* / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D017951:Antigen Presentation; D015796:HLA-B27 Antigen / Q000378:metabolism*; D006801:Humans; D010446:Peptide Fragments; D010455:Peptides / Q000378:metabolism*; D011485:Protein Binding / Q000276:immunology*; D051381:Rats; D014407:Tumor Cells, Cultured
D018528:ATP-Binding Cassette Transporters; D015796:HLA-B27 Antigen; D010446:Peptide Fragments; D010455:Peptides