Cytokine that acts as a ligand to CD40/TNFRSF5 (PubMed:1280226, PubMed:31331973). Costimulates T-cell proliferation and cytokine production (PubMed:8617933). Its cross-linking on T-cells generates a costimulatory signal which enhances the production of IL4 and IL10 in conjunction with the TCR/CD3 ligation and CD28 costimulation (PubMed:8617933). Induces the activation of NF-kappa-B (PubMed:15067037, PubMed:31331973). Induces the activation of kinases MAPK8 and PAK2 in T-cells (PubMed:15067037). Induces tyrosine phosphorylation of isoform 3 of CD28 (PubMed:15067037). Mediates B-cell proliferation in the absence of co-stimulus as well as IgE production in the presence of IL4 (By similarity). Involved in immunoglobulin class switching (By similarity). Acts as a ligand for integrins, specifically ITGA5:ITGB1 and ITGAV:ITGB3; both integrins and the CD40 receptor are required for activation of CD40-CD40LG signaling, which have cell-type dependent effects, such as B-cell activation, NF-kappa-B signaling and anti-apoptotic signaling. Homotrimer (PubMed:8626375, PubMed:11676606, PubMed:8589998). Interacts with isoform 3 of CD28 (PubMed:15067037). CD40 ligand, soluble form: Exists as either a monomer or a homotrimer (PubMed:8626375, PubMed:31331973). Forms a ternary complex between CD40 and integrins for CD40-CD40LG signaling (PubMed:31331973). Release of soluble CD40L from platelets is partially regulated by GP IIb/IIIa, actin polymerization, and a matrix metalloproteinases (MMP) inhibitor-sensitive pathway. Specifically expressed on activated CD4+ T-lymphocytes. The soluble form derives from the membrane form by proteolytic processing. N-linked glycan is a mixture of high mannose and complex type. Glycan structure does not influence binding affinity to CD40. Not O-glycosylated. The disease is caused by variants affecting the gene represented in this entry. Belongs to the tumor necrosis factor family. CD40L defect database