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Structural and functional aspects of the Ly49 natural killer cell receptors
Author(s) -
Dimasi Nazzareno,
Biassoni Roberto
Publication year - 2005
Publication title -
immunology and cell biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.999
H-Index - 104
eISSN - 1440-1711
pISSN - 0818-9641
DOI - 10.1111/j.1440-1711.2005.01301.x
Subject(s) - mhc class i , biology , microbiology and biotechnology , major histocompatibility complex , receptor , natural killer cell , cytotoxic t cell , innate immune system , immune system , immunoglobulin superfamily , immunology , genetics , in vitro
Natural killer cells are part of the first line of innate immune defence against virus‐infected cells and cancer cells in the vertebrate immune system. They are called ‘natural’ killers because, unlike cytotoxic T cells, they do not require a previous challenge and preactivation to become active. The Ly49 NK receptors are type II transmembrane glycoproteins, structurally characterized as disulphide‐linked homodimers. They share extensive homology with C‐type lectins, and they are encoded by a multigene family that in mice maps on chromosome 6. A fine balance between inhibitory and activating signals regulates the function of NK cells. Inhibitory Ly49 molecules bind primarily MHC class I ligands, whereas the ligands for activating Ly49 molecules may include MHC class I, but also interestingly MHC class I‐like molecules expressed by viruses, as is the case for Ly49H, which binds the m157 gene product of murine cytomegalovirus. In this study, we review the function and X‐ray crystal structure of the Ly49 NK cell receptors hitherto determined (Ly49A, Ly49C and Ly49I), and the structural features of the Ly49/MHC class I interaction as revealed by the X‐ray crystal structures of Ly49A/H‐2D d and the recently determined Ly49C/H‐2K b .