A protein that is encoded by the EREG gene, Epiregulin is a 46 amino acid protein which belongs to the Epidermal Growth Factor (EGF) group of peptide hormones. Similar to the other members of the EGF family, Epiregulin is expressed as a transmembrane proform, in which the mature, soluble form is stored within the extracellular region of the preform.
The EGF family are cleaved by disintegrin and metalloproteinase enzyme, which allows for the release of 50 amino acids. The mature growth factors then bind to parts of the ECG receptor family; this group is made up of EGF receptor EGFR/ErbB1, ErbB2, ErbB3, and ErbB4. An ErbB receptor can either homodimerize along with an identical member of the ErbB group or can heterodimerize with a different member of the ErbB family; receptor dimerization allows tyrosine phosphorylation or one receptor by another receptor. This cross-linkage allows binding sites to be created for effective proteins that posses phosphotyrosine binding motifs, allowing the receptors to couple various signalling cascades.
Consisting primarily of 46 amino acids, Epiregulin has a secondary structure of around 30 percent of B-sheet in the strange. Some of its residues create loops and turns due to the bonding of the hydrogen. The percentage of B-sheet in epiregulin will depend on the domain and the secondary structures that are occupied. It is the polymeric molecules of epiregulin that hold the formula weight of 5280.
In most proteins, structural proteins have connections in all B motif, meaning that the polypeptide chains do not create a crossover connection, or at least, this kind of connection is yet to be observed. Epiregulin is one of the proteins that have a typical connection in all B motif, and as it forms a chain in all B motif, it can also create a hairpin structural motif. This is when two adjacent antiparallel B strands are connected by a B turn.
A member of the epidermal growth factor family, epiregulin can function as a ligand of the EGFR (epidermal growth factor receptor), as well as a ligand of most members of the ERBB group of tyrosine-kinase receptors. The secondary structure of the C-terminus is unique to other epidermal growth factor group ligands because it lacks hydrogen bonds. The difference in structure seen at the C-terminus may provide an explanation for the lack of binding ability of the epiregulin to the ERBB receptors.
The combination of ECG hormones in the ErbB group receptors can regulate the proliferation, differentiation, and function of various tissues in humans deregulated signalling of this network is a trademark of various different human malignancies. Epiregulin plays a role in inflammation, wound healing, normal physiology, and human malignancies. From angiogenesis, vascular remodeling, and inflammation, including liver repair, ovary follicle formation, and other reproductive purposes, to arthritis, wound healing, and cancer, including liver, breast, lung, gastric, and bladder cancers, epiregulin plays a role in a range of human disease and health conditions, and the potential healing and treatment processes of them as well.