Soluble HLA-DQ2 expressed in S2 cells copurifies with a high affinity insect cell derived protein |
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Authors: | Ulrike Jüse Burkhard Fleckenstein Elin Bergseng Ludvig M Sollid |
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Institution: | (1) Centre for Immune Regulation, Institute of Immunology, University of Oslo, Oslo, Norway;(2) Institute of Immunology, Rikshospitalet University Hospital, 0027 Oslo, Norway |
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Abstract: | We here describe that soluble HLA-DQ2 (sDQ2) molecules, when expressed in Drosophila melanogaster S2 insect cells without a covalently tethered peptide, associate tightly with the D. melanogaster calcium binding protein DCB-45. The interaction between the proteins is stable in S2 cell culture and during affinity purification,
which is done at high salt concentrations and pH 11.5. After affinity purification, the sDQ2/DCB-45 complex exists in substantial
quantities next to a small amount of free heterodimeric sDQ2 and large amounts of aggregated sDQ2 free of DCB-45. Motivated
by the stable complex formation and our interest in the development of reagents which inhibit HLA-DQ2 peptide binding, we
have further characterized the sDQ2/DCB-45 interaction. Several lines of evidence indicate that an N-terminal fragment of
DCB-45 is involved in the interaction with the peptide binding groove of sDQ2. Further mapping of this fragment of 54 residues
identified a pentadecapeptide with high affinity for sDQ2 which may serve as a lead compound for the design of HLA-DQ2 blockers. |
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Keywords: | HLA sDQ2 DCB-45 S2 Protein interactions Peptide binding |
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