EGF stands for Epidermal Growth Factor which is a protein found in both humans and other animals such as mice. When present in humans, it’s often located in various tissues of the body. Two of the most common areas are the parotid gland and submandibular gland. Upon discovering human EGF for the first time, it was called urogastrone. This name is largely unused now, though some sectors still use it to refer to the epidermal growth factor. Epidermal growth factor is often found in various liquids throughout the body, particularly; urine, milk, blood plasma, and saliva. It is thought that epidermal growth factor is produced largely thanks to testosterone stimulation. As such, it’s often more commonly present in male bodies than female.
Function & Interactions
The main function of EGF is to help encourage cell growth. It does this by binding with a receptor known as EGFR. This is the key thing that epidermal growth factor is known to interact with. When this binding occurs, it leads to a rapid increase in the cell count, differentiation within cells, and cell survival.
Furthermore, there have been studies linking different types of EGF with additional functions in the body. This is particularly prevalent in salivary EGF proteins. When EGF is produced in the salivary glands, it is linked to maintaining and repairing gastric tissue, along with oro-oesophagal maintenance. As a consequence, many problems within this part of the body can be healed thanks to EGF. The best example of this is ulcers in the mouth and throat, which can be healed when this protein is secreted
As previously mentioned, EGF acts when it binds to its receptor; EGFR. This binding occurs on the surface of the cell, and helps stimulate a process called ligand-induced dimerization. When this happens, there is a reaction in the protein that helps activate it's intrinsic protein-tyrosine kinase properties. As a result, this will then turn on a process that transmits a signal through the cell, which will end in various changes in the cell on a biological level. The main things that happen during this time are an increase in calcium levels within the cell, along with heightened protein synthesis and glycolysis. To coincide with this, there are also increases in certain gene expressions as well
The structure of EGF is somewhat similar to many other proteins as they’re all part of the same family. Every protein in this family can boast the same conserved amino acid sequence. In this sequence, there are a total of six cysteine residues that merge together to create three intramolecular disulfide bonds. Consequently, the formation of these bonds leads to the creation of three structural loops. These structural loops have a high significance as they’re responsible for inducing high-affinity binding that connects all EGF-family proteins to their cell-surface receptors.
Epidermal growth factor is often referred to as a 6-kDa protein due to its structural makeup. As well as the six cysteine residues and three intramolecular disulfide bonds, there are also 53 amino acid residues present.