CD154, also known as CD40 ligand (CD40L), is a 39 kDa type II membrane glycoprotein of the TNF family. It has been reported that CD154 binding with its ligand, CD40, is required for the proteolysis of membrane-bound CD154 and the subsequent release of soluble CD154 (sCD154) by activated platelets. Soluble CD154 is an 18 kDa fragment comprised of residues 113–261 of the membrane-bound CD154 molecule and remains a functional trimer retaining its ability to bind receptors. The CD154 homotrimer is nonconstitutively expressed on different cell types, including activated T lymphocytes, basophils, eosinophils, monocytes, macrophages, natural killer cells, B lymphocytes, platelets, and dendritic cells as well as endothelial, smooth muscle, and epithelial cells. Accumulating evidence indicates that CD154 can bind to receptors other than CD40, namely, the integrins αIIbβ3, α5β1, and αMβ2.
Anti-Human CD154/CD40L (24-31)-168Er—100 Tests