The function of KLRB1 (killer cell lectin like receptor B1, Ensembl gene identifier ENSG00000111796) is as follows. Plays an inhibitory role on natural killer (NK) cells cytotoxicity. Activation results in specific acid sphingomyelinase/SMPD1 stimulation with subsequent marked elevation of intracellular ceramide. Activation also leads to AKT1/PKB and RPS6KA1/RSK1 kinases stimulation as well as markedly enhanced T-cell proliferation induced by anti-CD3. Acts as a lectin that binds to the terminal carbohydrate Gal-alpha(1,3)Gal epitope as well as to the N- acetyllactosamine epitope. Also binds to CLEC2D/LLT1 as a ligand and inhibits NK cell-mediated cytotoxicity as well as interferon-gamma secretion in target cells. {ECO:0000269|PubMed:16455998, ECO:0000269|PubMed:16925668, ECO:0000269|PubMed:8077657}.