Calcium-dependent lectin that acts as a pattern recognition receptor (PRR) of the innate immune system: recognizes damage-associated molecular patterns (DAMPs) of pathogen-associated molecular patterns (PAMPs) of bacteria and fungi (PubMed:23602766, PubMed:23911656). The PAMPs include alpha-mannans on C.albicans hypheas and mycobacterial trehalose 6,6'-dimycolate (TDM) (PubMed:23602766, PubMed:23911656). Interacts with signaling adapter Fc receptor gamma chain/FCER1G, likely via CLEC4E, to form a functional complex in myeloid cells (By similarity). Binding of mycobacterial TDM or C.albicans alpha-mannans to this receptor complex leads to phosphorylation of the immunoreceptor tyrosine-based activation motif (ITAM) of FCER1G, triggering activation of SYK, CARD9 and NF-kappa-B, consequently driving maturation of antigen-presenting cells and shaping antigen-specific priming of T-cells toward effector T-helper 1 and T-helper 17 cell subtypes (PubMed:23602766, PubMed:23911656). The heterodimer formed with CLEC6A is active against fungal infection (PubMed:23911656). Functions as an endocytic receptor (PubMed:14971047). May be involved in antigen uptake at the site of infection, either for clearance of the antigen, or for processing and further presentation to T-cells (PubMed:14971047). Heterodimer with CLEC4E; disulfide-linked (By similarity). CLEC4E acts as a bridge for interaction between CLEC4D and FCER1G to form a functional complex (By similarity). Heterodimer with CLEC6A; this heterodimer forms a pattern recognition receptor (PRR) against fungal infection (PubMed:23911656). Expressed weakly in peripheral blood leukocytes, bone marrow and spleen. Expression is confined mostly in monocytes and macrophage and seems to be up-regulated by IL-6, IL-10, TNF-alpha and IFN-gamma. By autocrine inflammatory stimuli. MCL