C-Type Lectin Domain Family 4, Member D (CLEC4D)

CLEC4D has a 21-amino acid cytoplasmic tail, followed by a 20-amino acid transmembrane domain and an extracellular region composed of a 42-amino acid stalk region with 3 cysteines and a 132-amino acid CRD with 3 potential N-glycosylation sites. RT-PCR analysis identified a potential CLEC4D splice variant encoding a protein lacking the CRD. Northern blot analysis detected 1.2- and 2.4-kb transcripts in bone marrow and peripheral blood leukocytes, with faint expression in spleen. CLEC4D expression was induced in monocyte-derived macrophages incubated with IL6  and other cytokines, but it was downregulated by lipopolysaccharide. Flow cytometric and confocal microscopy analysis showed that cross-linking induced CLEC4D internalization, suggesting that it is an endocytic receptor.