Plays an inhibitory role on natural killer (NK) cells and T-cell functions upon binding to their non-MHC ligands. May mediate missing self recognition by binding to a highly conserved site on classical cadherins, enabling it to monitor expression of E-cadherin/CDH1, N-cadherin/CDH2 and R-cadherin/CDH4 on target cells. Forms a monomer and homodimer; disulfide-linked. Interacts (via ITIM motif) with PTPN11 and INPP5D. Expressed specifically on natural killer (NK) cells and T-cells, mainly CD8 T-cells. By pathogens and viruses infections. Contains 1 copy of a cytoplasmic motif that is referred to as the immunoreceptor tyrosine-based inhibitor motif (ITIM). This motif is involved in modulation of cellular responses. Upon phosphorylation of ITIM motif KLRG1 associates with the two phosphatases PTPN11 and INPP5D (By similarity).