O'Callaghan CA., Watson SP.
The C-type lectin-like protein (CLEC-2) is a type 2 transmembrane protein with an extracellular C-type lectin-like domain and a short cytoplasmic domain containing a single YXXL motif. CLEC-2 is a receptor expressed on the surface of platelets. Ligand binding triggers platelet activation, including stimulation of powerful aggregation and secretion. Ligand interaction triggers phosphorylation of tyrosine 7 in the cytoplasmic YXXL motif by activation of Src kinases. CLEC-2 phosphorylation triggers interaction with the tyrosine kinase Syk, which in turn phosphorylates a series of downstream signaling proteins, including PLCγ2. There are two known ligands for CLEC-2, which are the endogenous protein podoplanin and the snake venom protein rhodocytin. Both proteins interact directly with CLEC-2 with micromolar affinities. Podoplanin is expresed in kidney podocytes, type 1 lung alveolar cells and lymphatic endothelial cells. The function of CLEC-2 is not known.