If there is a Gs alpha subunit gain-of-function mutation, this results in
**Core Concept**
Gs alpha subunit is a key component of G protein-coupled receptors (GPCRs), which play a crucial role in signal transduction within cells. A gain-of-function mutation in the Gs alpha subunit leads to an increase in its activity, resulting in an exaggerated response to its ligands.
**Why the Correct Answer is Right**
A gain-of-function mutation in the Gs alpha subunit causes an increase in the production of cyclic adenosine monophosphate (cAMP) within the cell. This is due to the enhanced activity of the Gs alpha subunit, which activates adenylyl cyclase, the enzyme responsible for cAMP synthesis. As a result, the downstream signaling pathways that rely on cAMP are overactivated, leading to various physiological effects.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because a gain-of-function mutation in the Gs alpha subunit would not result in decreased cAMP production.
* **Option B:** This option is incorrect because a gain-of-function mutation in the Gs alpha subunit would not result in increased phospholipase C (PLC) activity, which is associated with a different G protein subunit (Gs or Gi).
* **Option C:** This option is incorrect because a gain-of-function mutation in the Gs alpha subunit would not result in decreased cellular proliferation, as the overactivation of cAMP-dependent pathways often leads to increased cell growth and proliferation.
**Clinical Pearl / High-Yield Fact**
A gain-of-function mutation in the Gs alpha subunit is associated with McCune-Albright syndrome, a disorder characterized by café-au-lait skin spots, polyostotic fibrous dysplasia, and various endocrine disorders, including precocious puberty.
**Correct Answer: C. Increased cellular proliferation.**