Question

Consider a mutant liver cell isolated from a liver cancer patient. This cell contains about 104 molecules of active protein kinase A, even in the absence of epinephrine. What is a reasonable genetic explanation?

Answer 1

A reasonable genetic explanation for the mutant liver cell containing about 104 molecules of active protein kinase A, even in the absence of epinephrine, could be a mutation in a gene that encodes for a protein involved in the regulation of protein kinase A.

Step-by-step explanation:

Based on the given information, a reasonable genetic explanation for the mutant liver cell containing about 104 molecules of active protein kinase A, even in the absence of epinephrine, could be a mutation in a gene that encodes for a protein involved in the regulation of protein kinase A. This mutation could result in the constitutive activation of protein kinase A, leading to elevated levels of the active form of the enzyme in the absence of the usual signaling molecules such as epinephrine.

For example, a mutation in a gene encoding a G-protein-linked receptor that normally binds epinephrine could result in a receptor that is always in an active state, leading to the continuous activation of protein kinase A even without the presence of epinephrine. Another possible genetic explanation could be a mutation in a gene encoding a protein involved in the regulation of protein kinase A activity, such as a phosphatase or an inhibitor, resulting in an inability to inactivate or inhibit the enzyme, leading to persistently high levels of active protein kinase A.

These genetic mutations could disrupt the normal regulation of protein kinase A activity and contribute to the dysregulation of cellular processes such as cell division and metabolism, which are known to be regulated by protein kinase A signaling.