C-type lectin-like receptor that serves as a platelet receptor for the lymphatic endothelial marker PDPN (PubMed:18215137). Plays an essential role in blood/lymphatic vessel separation and thrombus formation through homophilic association (PubMed:22556408). Acts as a negative regulator of lymphatic endothelial cell behavior by inhibiting proliferation, migration, and tube formation (PubMed:22556408). Upon ligand binding, triggers a signaling cascade via sequential activation of SRC and SYK tyrosine kinases, leading to activation of PLCG2 (PubMed:18955485). Through this pathway, mediates platelet adhesion, aggregation, and secretion in response to PDPN- expressing cells. During embryonic development, plays a central role in cerebrovascular formation and blood/lymphatic vessel separation. Interacts with PDPN on neuroepithelial cells to promote platelet activation, thereby ensuring maturation and integrity of cerebrovascular structures and preventing hemorrhage. {ECO:0000269|PubMed:18215137, ECO:0000269|PubMed:18955485, ECO:0000269|PubMed:22556408}. (Microbial infection) Acts as a receptor for the platelet- aggregating snake venom protein rhodocytin. Rhodocytin binding leads to tyrosine phosphorylation and this promotes the binding of spleen tyrosine kinase (SYK) and initiation of downstream tyrosine phosphorylation events and activation of PLCG2 (PubMed:16174766, PubMed:18955485). {ECO:0000269|PubMed:18955485, ECO:0000305|PubMed:16174766}. (Microbial infection) Acts as an attachment factor for Human immunodeficiency virus type 1 (HIV-1) and facilitates its capture by platelets (PubMed:16940507). . This is the function of CLEC1B (C-type lectin domain family 1 member B, ENSG00000165682).