The CD154, also known as CD40 ligand pathway is widely known for its significant role in immune regulation and homeostasis. It is identified by an antibody which is expressed on many cells in the immune system, for example, on dentritic cells, on B cells, on basophils, eosinophils, and monocytes. It is also can be found on epithelial cells, on smooth muscle cells, on keralino cytes, and on fibroblasts. The main function of CD40 is that it regulate a myriad spectrum of cellular and molecular processes such as progression and initiation of cellular and humoral adaptive immunity.
In general, there are two families of the costimulatory molecules which are molecules from the CD28-B7 costimulatory …show more content…
The process starts by binding of heat shock proteins to a large range of peptides under cellular stress conditions or during synthesis, after this reaction they can reach the extracellular space following to viral lysis or nacrosis, they also can carry antigenic peptides for cross-priming. Various number of bacteria can upregulate chemokines such as MIP-1α, MIP-1β, and RANTES across binding to CD40. The interactions of Hsp-70-peptide-CD40 can lead to the uptake of the Hsp70-peptide complex, then it will display the loaded peptide on MHC class I or II as a result.
Structure and molecular characteristics of CD40
CD40 is a 43-48 kDa glycoprotein; it is consisted of 277 amino acid residues. It is a member of (TNFR) family, which stands for the tumour necrosis factor receptor family. The extracellular part of the CD40 is composed of various cysteine rich repeats as all the other members of this family. The four extracellular domains are consisted of two types of modular units as shown in Figure 1, each one of those units is stabilised by one or two disulfide bonds.
CD40 is made up of a single membrane spanning domain and expose the N-terminus of the protein to the exterior (type I membrane protein). Actually, CD40 is a hydrophobic protein with an acidic pI of 3.2. There are many recognition sites for the intermolecular proteins in the cytoplasmic domain of CD40 such