Killer activation receptor

When a KAR binds to MICA and MICB molecules on the surface of an infected cell (or a tumor cell), a KIR examines the levels of MHC class I of this target cell. If the MHC class I levels are enough, killing of the cell doesn't proceed (left), but if they aren't, the killing signal proceeds and the cell is eliminated (right).

Killer Activation Receptors (KARs) are receptors expressed on the plasma membrane (cell membrane) of Natural Killer cells (NK cells). KARs work together with Killer Inhibitory Receptors (abbreviated as KIRs in the text), which inactivate KARs in order to regulate the NK cells functions on hosted or transformed cells[1].These receptors have a broad binding specificity and are able to broadcast opposite signals. It is the balance between these competing signals that determines if the cytotoxic activity of the NK cell and apoptosis of distressed cell occurs.[2]

  1. ^ Flaherty, Dennis K. (2012). Immunology for Pharmacy. Elsevier/Mosby. ISBN 978-0-323-06947-2. Retrieved 2024-02-27.
  2. ^ Coico, Richard; Sunshine, Geoffrey (2015). Immunology: a short course (7th ed.). Chichester: Wiley Blackwell. ISBN 978-1-118-39689-6.