Molecular characterization of two novel C-type lectin-like receptors, one of which is selectively expressed in human dendritic cells.

We have identified two human C-type lectin-like receptors, CLEC-1 and CLEC-2. Both display a single carbohydrate recognition domain and a cytoplasmic tyrosine-based motif. They are homologous to the NK cell receptors NKG2s and CD94 and also to the oxidized low-density lipoprotein receptor 1. CLEC-1 and CLEC-2 are preferentially transcribed in dendritic cells (DC) and in the liver, respectively. Following transient transfection in COS cells, CLEC-1 is expressed intracellularly, perhaps requiring an associated chain to reach the cell surface. CLEC-2 is expressed on the surface of transfected cells as a protein of approximately 33 kDa. CLEC-1 and CLEC-2 genes map to human chromosome 12, most likely in linkage with the NK gene complex (NKC). Thus, the NKC may encode C-type lectin-like receptors expressed not only in NK cells but also in other cells, and at least one of these is of potential importance in regulating DC function.