Lectin and epidermal growth factor domains of P-selectin at physiologic density are the recognition unit for leukocyte binding

摘要: P-selectin is an integral membrane glycoprotein on stimulated platelets and endothelial cells that serves as a receptor for leukocytes. To estimate the density of in membranes necessary to support adhesion, we incorporated purified at varying concentrations into phospholipid bilayers encapsulated glass microspheres. Maximal binding these lipospheres HL60 cells, ligand- expressing cell line, was approached about 100 molecules per microns 2; half-maximal observed 50 60 2. Compatible results were obtained with expressed Chinese hamster ovary cells. The estimated be 150 200 molecules/microns identify domains required binding, chimeras L-selectin stably clones physiologic selected. Chimeras containing lectin epidermal growth factor (EGF) or lectin, EGF, short consensus repeats bound equivalently, but chimera domain alone much less well. These indicate physiologically relevant surfaces, EGF are together optimal leukocyte binding.