Structural and functional aspects of the Ly49 natural killer cell receptors

Nazzareno Dimasi, Roberto Biassoni

Research output: Contribution to journalArticlepeer-review


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-2Dd and the recently determined Ly49C/H-2Kb.

Original languageEnglish
Pages (from-to)1-8
Number of pages8
JournalImmunology and Cell Biology
Issue number1
Publication statusPublished - Feb 2005


  • Activating receptor
  • Crystal structure
  • Immunoreceptor
  • Inhibitory receptor
  • Ly49
  • Ly49/ MHC complex
  • MHC class I
  • NK cell
  • NK cell receptor

ASJC Scopus subject areas

  • Immunology
  • Clinical Biochemistry
  • Cell Biology


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