Download Mendeley2 A crystal structure of an extracellular fragment of human CD40 ligand.
Karpusas, M., Hsu, Y.M., Wang, J.H., Thompson, J., Lederman, S., Chess, L., Thomas, D.(1995) Structure 3: 1031-1039
- PubMed: 8589998
- DOI: https://doi.org/10.1016/s0969-2126(01)00239-8
- Primary Citation of Related Structures:
1ALY - PubMed Abstract:
The CD40 ligand (CD40L) is a member of the tumor necrosis factor (TNF) family of proteins and is transiently expressed on the surface of activated T cells. The binding of CD40L to CD40, which is expressed on the surface of B cells, provides a critical and unique pathway of cellular activation resulting in antibody isotype switching, regulation of apoptosis, and B cell proliferation and differentiation. Naturally occurring mutations of CD40L result in the clinical hyper-IgM syndrome, characterized by an inability to produce immunoglobulins of the IgG, IgA and IgE isotypes. We have determined the crystal structure of a soluble extracellular fragment of human CD40L to 2 A resolution and with an R factor of 21.8%. Although the molecule forms a trimer similar to that found for other members of the TNF family, such as TNF alpha and lymphotoxin-alpha, and exhibits a similar overall fold, there are considerable differences in several loops including those predicted to be involved in CD40 binding. The structure suggests that most of the hyper-IgM syndrome mutations affect the folding and stability of the molecule rather than the CD40-binding site directly. Despite the fact that the hyper-IgM syndrome mutations are dispersed in the primary sequence, a large fraction of them are clustered in space in the vicinity of a surface loop, close to the predicted CD40-binding site.
Organizational Affiliation:
Biogen, Inc., Cambridge, MA 02142, USA.
