PLoS ONE (Apr 2011)

LILRA3 binds both classical and non-classical HLA class I molecules but with reduced affinities compared to LILRB1/LILRB2: structural evidence.

  • Myongchol Ryu,
  • Yong Chen,
  • Jianxun Qi,
  • Jun Liu,
  • Zheng Fan,
  • Gol Nam,
  • Yi Shi,
  • Hao Cheng,
  • George F Gao

DOI
https://doi.org/10.1371/journal.pone.0019245
Journal volume & issue
Vol. 6, no. 4
p. e19245

Abstract

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Structurally, Group 1 LILR (Leukocyte Immunoglobulin (Ig)-Like Receptor, also known as Ig-like transcripts, ILT; Leukocyte Ig-like receptor, LIR; and CD85) members are very similar in terms of the HLAIs (human leukocyte antigen class I molecules) binding region and were hypothesized that they all bind to HLAIs. As one of the Group 1 LILRs, LILRA3 is the only secretory LILR and may greatly control the inhibitory immune response induced by LILRB1, LILRB2, and other HLA-binding LILR molecules like LILRA1. Nevertheless, little was known about the binding of LILRA3 to HLAIs. In this report, we present the crystal structure of the LILRA3 domain 1 (D1) and evaluate the D1 and D1D2 (domain 1 and domain 2) binding to classical and non-classical HLAIs using BIAcore® surface plasmon resonance analysis (SPR). We found that LILRA3 binds both classical HLA-A*0201 and non-classical HLA-G1 but with reduced affinities compared to either LILRB1 or LILRB2. The polymorphic amino acids and the LILRA3 D1 structure support this notion.