KLRG1 (killer cell lectin?like receptor G1), also called MAFA (mast cell function associated), is an inhibitory type II transmembrane glycoprotein of the C?type lectin family, designated CLEC15A.Within the ECD, Human KLRG1 shares 57% and 80% aa sequence identity with mouse and rat KLRG1, respectively.KLRG1 is expressed on subpopulations of CD8+, CD4+, regulatory, and gamma/delta T cells as well as on NK cells. KLRG1 is expressed on T cells found in cord blood, but it is down?regulated postnatally and is subsequently re?expressed on antigen?exposed T cells. It is expressed by a greater proportion of CD8+ T cells in the elderly and by virus?specific CD8+ T cells during chronic virus infection. KLRG1 binds to E-, N-, and R-Cadherins, triggering ITIM?dependent KLRG1 signaling and inhibition of T cell activation. The response is bi?directional, as KLRG1 binding to E?Cadherin on dendritic cells (DC) can induce an anti?inflammatory DC phenotype (increased IL?10 production and decreased IL?6 and TNF? alpha production).