Receptor for KLRB1B that protects target cells against natural killer cell-mediated lysis (PubMed:14990792, PubMed:16751398). Inhibits osteoclast formation (PubMed:11278931, PubMed:12374791). Binds high molecular weight sulfated glycosaminoglycans (PubMed:15123656). Homodimer; disulfide-linked. Detected in fetal heart, brain, lung, chondrocytes, perichondrium and osteoblasts, and in adult splenocytes, thymocytes, lymph-node cells, osteoblasts, growth plate chondrocytes and skeletal muscle overlying the bone (at protein level). Ubiquitous. Detected in thymus, bone marrow, lung, gut, heart, skeletal muscle, ovary, spleen, ileum, liver and kidney. Constitutively expressed in bone marrow cells. Down-regulated by treatment with 1,25-dihydroxyvitamin D3. Up-regulated in calvarial osteoblast cells by IL-1alpha, IL11, and 1,25-dihydroxyvitamin D3. N-glycosylated.