Qa-1b binds conserved class I leader peptides derived from several mammalian species.
Qa-1b binds a peptide (AMAPRTLLL), referred to as Qdm (for Qa-1 determinant modifier), derived from the signal sequence of murine class Ia molecules. This peptide binds with high affinity and accounts for almost all of the peptides associated with this molecule. Human histocompatibility leukocyte antigen (HLA)-E, a homologue of Qa-1b, binds similar peptides derived from human class Ia molecules and interacts with CD94/NKG2 receptors on natural killer cells. We used surface plasmon resonance to determine the ability of Qa-1b to bind related ligands representing peptides derived from the leaders of class I molecules from several mammalian species. All of the peptides reported to bind HLA-E bound readily to Qa-1b. In addition, peptides derived from leader segments of different mammals also bound to Qa-1b, indicating a conservation of this "Qdm-like" epitope throughout mammalian evolution. We have attempted to define a minimal peptide on a polyglycine backbone that binds Qa-1b. Our previous findings showed that P2 and P9 are important but not sufficient for binding to Qa-1b. Although a minimum peptide (GMGGGGLLL) bound Qa-1(b), its interaction was relatively weak, as were peptides sharing five or six residues with Qdm, indicating that multiple native residues are required for a strong interaction. This finding is consistent with the observation that this molecule preferentially binds this single ligand.
Kurepa
Z
Z
Immunology Graduate Program, University of Texas Southwestern Medical Center at Dallas 75235, USA.
Hasemann
C A
CA
Forman
J
J
D000595:Amino Acid Sequence; D000818:Animals; D002415:Cats; D002417:Cattle; D002460:Cell Line; D017124:Conserved Sequence; D004285:Dogs; D004306:Dose-Response Relationship, Immunologic; D004331:Drosophila melanogaster; D006071:Gorilla gorilla; D006680:HLA Antigens / Q000378:metabolism; D015395:Histocompatibility Antigens Class I / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D002679:Pan troglodytes; D010446:Peptide Fragments; D010455:Peptides / Q000276:immunology / Q000378:metabolism*; D010542:Peromyscus; D011485:Protein Binding / Q000276:immunology; D021382:Protein Sorting Signals / Q000276:immunology / Q000378:metabolism*; D051381:Rats; D000097625:HLA-E Antigens
D006680:HLA Antigens; D015395:Histocompatibility Antigens Class I; D010446:Peptide Fragments; D010455:Peptides; D021382:Protein Sorting Signals; D000097625:HLA-E Antigens; C032907:Q surface antigens; C090580:Qdm protein, mouse