Killer Cell Immunoglobulin Like Receptor 2DS4 (KIR2DS4)

Using primers known to amplify HLA-C-specific NK receptors to screen clones with NK triggering activity, Bottino et al. (1996) also isolated a KIR2DS4 cDNA, which they termed KKA3. Sequence analysis revealed that KIR2DS4 encodes a deduced 304-amino acid protein with an extracellular domain similar to that of KIR2D p58 receptors; however, in the transmembrane region, there is a charged lysine residue, and the cytoplasmic tail has only 39 amino acids with no ITIM (immunoreceptor tyrosine-based inhibitory motif). KIRs with short cytoplasmic tails are associated with NK cell triggering rather than inhibition. Immunoprecipitation analysis showed that KIR2DS4 is expressed in 2 forms, one of 35 to 45 kD and the other of 55 to 58 kD. Flow cytometry analysis showed that KIR2DS4, unlike KIR2DS1 and KIR2DS2, was expressed in only a minority of individuals tested.