[PDF][PDF] The inhibitory receptor LIR-1 uses a common binding interaction to recognize class I MHC molecules and the viral homolog UL18

TL Chapman, AP Heikema, PJ Bjorkman - Immunity, 1999 - cell.com
TL Chapman, AP Heikema, PJ Bjorkman
Immunity, 1999cell.com
LIR-1 is a class I MHC receptor related to natural killer inhibitory receptors (KIRs). Binding of
LIR-1 or KIRs to class I molecules results in inhibitory signals. Unlike individual KIRs, LIR-1
recognizes many class I alleles and also binds UL18, a human cytomegalovirus class I MHC
homolog. Here, we show that LIR-1 interacts with the relatively nonpolymorphic α3 domain
of class I proteins and the analogous region of UL18 using its N-terminal immunoglobulin-
like domain. The> 1000-fold higher affinity of LIR-1 for UL18 than for class I illustrates how a …
Abstract
LIR-1 is a class I MHC receptor related to natural killer inhibitory receptors (KIRs). Binding of LIR-1 or KIRs to class I molecules results in inhibitory signals. Unlike individual KIRs, LIR-1 recognizes many class I alleles and also binds UL18, a human cytomegalovirus class I MHC homolog. Here, we show that LIR-1 interacts with the relatively nonpolymorphic α3 domain of class I proteins and the analogous region of UL18 using its N-terminal immunoglobulin-like domain. The >1000-fold higher affinity of LIR-1 for UL18 than for class I illustrates how a viral protein competes with host proteins to subvert the host immune response. LIR-1 recognition of class I molecules resembles the CD4–class II MHC interaction more than the KIR–class I interaction, implying a functional distinction between LIR-1 and KIRs.
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