TNFSF5 (CD40 Ligand)

CD40 ligand (CD40L), also known as CD154, TNFSF5, TRAP or gp39, is a 260 amino acid type II transmembrane glycoprotein belonging to the TNF family. Murine CD40L consists of a 22 aa cytoplasmic domain, a 24 aa transmembrane domain, and 214 aa extracellular domain bearing a single glycosylation site. CD40L is expressed predominantly on activated CD4+ T lymphocytes, and also found in other types of cells, including NK cells, mast cells, basophils and eosinophils. Murine CD40L shares 78% amino acid sequence identity with human CD40L. Native bioactive soluble CD40L exists. Soluble human trimeric CD40L secreted by stimulated T cells has been shown to be generated by proteolysis in the microsomes. Both membrane bound and soluble CD40L induce similar effects on B cells.