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Epitope mapping of Ly‐49G and G‐like receptors: CK‐1 antibody defines a polymorphic site of functional interaction with class I ligand
Author(s) -
Osman Mohammed S.,
Silver Elizabeth T.,
Varghese Jay C.,
Chang Chew Shun,
Gong DongEr,
Audette Gerald F.,
Hazes Bart,
Kane Kevin P.
Publication year - 2005
Publication title -
journal of leukocyte biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.819
H-Index - 191
eISSN - 1938-3673
pISSN - 0741-5400
DOI - 10.1189/jlb.0704407
Subject(s) - ectodomain , biology , epitope , major histocompatibility complex , receptor , subfamily , antibody , genetics , microbiology and biotechnology , antigen , gene
Ly‐49 receptors regulate mouse natural killer cell functions. Members of the polymorphic Ly‐49 multigene family recognize specific alleles of major histocompatibility complex class I (MHC I) or MHC I‐like proteins. Previous studies have provided insight into the nature of Ly‐49A and ‐C interaction with their high‐affinity MHC I ligands, H‐2D d and K b , respectively. Unlike Ly‐49C, recognition of MHC I by Ly‐49A is regulated in part by residues within the β4–β5 loop of its ectodomain. Ly‐49A and ‐G are within the same Ly‐49 subfamily, and both receptors recognize D d . However, there have been no studies that define specific sites on Ly‐49G that mediate class I MHC recognition. The Ly‐49G receptors of different inbred mouse strains can differ as a result of amino acid polymorphisms within their ectodomains. In this report, we have generated a novel antibody, CK‐1, which recognizes Ly‐49G B6 and a Ly‐49G B6 ‐like receptor, Ly‐49M nonobese diabetic , but not Ly‐49G BALB/c . By exploiting the differences within ectodomains of C57BL/6 and BALB/c Ly‐49G allele products, we identified epitopes recognized by the Ly‐49G‐specific antibodies CK‐1 and Cwy‐3, whose epitopes mapped within the β4–β5 loop and the β1 strand, respectively, and were nonoverlapping. Although both antibodies specifically recognized the Ly‐49G B6 ectodomain, Cwy‐3 was unable to block its interaction with MHC I, and CK‐1 significantly inhibited it. The importance of residues within the β4–β5 loop in Ly‐49G recognition demonstrates that its interaction with MHC I is similar to that of Ly‐49A but not Ly‐49C.