Question

g You prepare a cell line that overexpresses a mutant form of epidermal growth factor receptor, or EGFR, in which the entire intracellular region of the receptor has been deleted. Predict the effect of overexpression of this construct on epidermal growth factor (EGF) signaling in this cell line. What will be the effect of the overexpression of this truncated receptor? EGFR will be unable to bind its ligand, blocking the signal and stopping cell growth. EGFR will not form a dimer in the presence of EGF, stopping normal cell growth. EGFR will form a dimer, but the kinases will not be activated and the signal will stop. EGFR will activate other proteins without dimerization, causing uncontrolled cell growth.

Answer 1

Answer:

The correct answer is the third statement.

Explanation:

The epidermal growth factor refers to a ligand that stimulates the epidermal growth factor receptor or EGFR. The EGFR refers to a receptor tyrosine kinase. With the binding of a ligand to a receptor, the phenomenon of dimerization takes place, which makes the receptor to cross-phosphorylate each other within the intracellular domain, this eventually results in the phosphorylation of the downstream signaling molecules.  

This transduction of signals eventually results in cell differentiation. However, when the intracellular domain is not present, the signal transduction cannot occur within the cell. Thus, if the mutated EGFR, that is, without intracellular domain gets overexpressed, the ligand combines with the mutated receptor, its dimerization takes place with the help of the extracellular domain, but it will not be able to perform signal transduction, due to the absence of intracellular domain. Therefore, dimerization of EGFR will take place, without performing cross phosphorylation, which will eventually prevent cell growth.