Abstract
The binding of killer cell Ig-like Receptors (KIR) to their Class I MHC ligands was shown previously to be characterized by extremely rapid association and dissociation rate constants. During experiments to investigate the biochemistry of receptor-ligand binding in more detail, the kinetic parameters of the interaction were observed to alter dramatically in the presence of Zn(2+) but not other divalent cations. The basis of this phenomenon is Zn(2+)-induced multimerization of the KIR molecules as demonstrated by BIAcore, analytical ultracentrifugation, and chemical cross-linking experiments. Zn(2+)-dependent multimerization of KIR may be critical for formation of the clusters of KIR and HLA-C molecules, the "natural killer (NK) cell immune synapse," observed at the site of contact between the NK cell and target cell.