Ly-49 receptors or killer cell lectin-like receptor subfamily A (KLRA), are a class of natural killer cell receptors. Receptor on natural killer (NK) cells for H-2d alleles inhibits the activity of NK cells thus preventing cell lysis. In the case of cancer or virally infected cells, MHC-I will often be downregulated in order to limit cytotoxic T cell mediated killing of the cell, whereby NK cells will lack Ly-49 inhibitory signal and be able to kill infected or cancerous target cells. The homologous human KLRAP1 gene has been classified as a transcribed pseudogene because all associated transcripts are candidates for nonsense-mediated decay (NMD).