Probable cell surface receptor that plays several roles in cellular fusion, cell differentiation, bone and immune homeostasis. Plays a role in TNFSF11-mediated osteoclastogenesis. Cooperates with OCSTAMP in modulating cell-cell fusion in both osteoclasts and foreign body giant cells (FBGCs). Participates in osteoclast bone resorption. Involved in inducing the expression of tartrate-resistant acid phosphatase in osteoclast precursors. Plays a role in haematopoietic stem cell differentiation of bone marrow cells toward the myeloid lineage. Inhibits the development of neutrophilic granulocytes. Plays also a role in the regulation of dendritic cell (DC) antigen presentation activity by controlling phagocytic activity. Involved in the maintenance of immune self-tolerance and avoidance of autoimmune reactions. Monomer. Homodimer. Isoform 1 interacts (via the C-terminus cytoplasmic tail) with OS9 isoform 1 (via the C-terminus tail); the interaction induces DCSTAMP redistribution to the endoplasmic reticulum-Golgi intermediate compartment. Isoform 1 interacts (via the C-terminus cytoplasmic tail) with OS9 isoform 2 (via the C-terminus tail) (By similarity). Interacts with CREB3. Localizes to the cell surface in osteoclasts and undifferentiated monocytes. Intracellular internalized DCSTAMP is detected in a fraction of RANKL-induced osteoclast precursor. Colocalizes with OS9 in the endoplasmic reticulum (ER) of immature dendritic cell (DC). Translocates from the endoplasmic reticulum to the intermediate/Golgi compartment upon maturation of DC in a OS9-dependent manner. Colocalizes with LAMP1 in endosomes (By similarity). Preferentially expressed by dendritic cells (DCs). Detected in both immature and mature DCs. Highly expressed in lymph nodes, lung, kidney and liver. Expressed at lower levels in pancreas, bone marrow, spleen, leukocytes, in freshly isolated peripheral blood mononuclear cells (PBMC) and B-cells. Not expressed in freshly isolated monocytes. Constitutively expressed in dendritic cells from day 3-8 in culture. Expression is down-regulated by dexamethasone and up-regulated by IL4/interleukin-4 in macrophages. Down-regulated in CD40L-activated dendritic cells. Several domains are necessary for interacting with OS9. The region in the cytoplasmic tail that is necessary for interaction with OS9, is also required for its transport (By similarity). Glycosylated.