The recombinant human CD300C consists of 166 amino acids with a molecular weight of 18.4 kDa. The apparent molecular mass of recombinant human CD300C is about 40-45 kDa in SDS-PAGE under reducing conditions due to glycosylation.The cluster of differentiation (CD) system is commonly used as cell markers in immunophynotyping. Different kinds of cells in the immune system can be identified through the surface CD molecules which associating with the immune function of the cell. Some of the CD molecules serve as receptors or ligands important to the cell through initiating a signal cascade which then alter the behavior of the cell. CD300C is present on the surface of natural killer cells, granulocytes, most myeloid cells, dendritic cells, and a subpopulation of T and B lymphocytes. Mouse CD300C has the characteristics of an activatory molecule capable of inducing cellular activation and effector function in most cells and macrophages. The ligand for CD300C is presently unknown.