Selectins: a family of adhesion receptors.

Recent data have shown that a group of cell surface proteins, originally studied independently as lymphocyte homing receptors or as activation-induced surface proteins of platelets and/or endothelial cells (Stoolman, 1989) are structurally related. Each is an integral membrane protein with an N-terminal, C-type lectin domain followed by an EGF-like module, multiple copies of the consensus repeat units characteristic of complement-binding proteins, a transmembrane segment, and a short cytoplasmic domain. The three known proteins having this structure are encoded by closely linked geneson the long arm of human and mouse chromosome 1 (Watson et al., 1990). The gene structures are related, and the genes clearly arose by gene duplication. These proteins are all involved in cell-cell adhesion events and constitute a new family of cell adhesion receptors. A wide variety of names are used to designate these proteins, owing to their independent discovery by different laboratories working in several fields. This diversity of nomenclature interferes with the dissemination of information about these proteins. After consultation among the researchers working on these proteins and other scientists, we propose that this family of proteins be named selectins to reflect the involvement of carbohydrate recognition in their functions. Individual members of the family will be designated by a prefix capital letter, as is done for the cadherins (e. g., E-, N-, P-). Letters can be chosen based on the source of the original discovery but are not intended to imply cell type specificity. The three known selectins are: