- Human pathology

Home > A. Molecular pathology > CD40LG


MIM.300386 Xq26

Tuesday 16 October 2007


Definition: The CD40LG gene encodes a transmembrane molecule, CD40 ligand (CD40L), found on T cells.

Human CD40L is a 39 kDa, type II (extracellular C-terminus) transmembrane glycoprotein that was originally identified on the surface of CD4+ T cells.

With a predicted molecular weight of 29 kDa, CD40L is 261 aa residues long, with a 22 aa residue cytoplasmic domain, a 24 aa residue transmembrane segment, and a 215 aa residue extracellular region.

Human to mouse, CD40L is 73% identical at the aa sequence level and mouse CD40L is apparently active in humans.

Although usually considered to be a membrane bound protein, natural, proteolytically cleaved 15-18 kDa soluble forms of CD40L with full biological activity have also been described.

Like TNF-alpha (TNFA), CD40L is reported to form natural trimeric structures. Cells known to express CD40L include B cells, CD4+ and CD8+ T cells, mast cells and basophils, eosinophils, dendritic cells, and monocytes, NK cells, and gd T cells.


- CD40L deficiency (X-linked hyper-IgM syndrome) (HIGM1) (MIM.308230)

  • Mutations in CD40 or CD40 ligand (CD40L) are known to cause hyper-IgM syndrome, in which T-cell and B-cell interaction is disrupted, thus preventing isotype switching from IgM and a subsequent selective increase in IgM at the expense of other immunoglobulins.