KLRA1 (also known and Ly49L) is a member of the LY49 family of receptors Natural killer (NK) cells that bind to major histocompatibility complex (MHC) class 1. These proteins are classified as either activating or inhibitory receptors based on whether they possess an immunoreceptor tyrosine-based inhibitory motif (ITIM) in their cytoplasmic region (for inhibitory receptors), or an immunoreceptor tyrosine-based activation motif (ITAM) that transmits activating signals resulting in phosphorylation of several substrates. KLRA1 is thought to be an activating receptor, inducing DAP12 phosphorylation in response to antibody-mediated cross-linking of KLRA1 on NK cells. At least three isoforms of KLRA1 are known to exist.