Which is not involved as second messenger in `Ca^(2+)` mediated hormone ?

Options

A. `IP^(3)`
B. `DAG`
C. `cAMP`
D. Phospholipase

Answer

To solve the question of which is not involved as a second messenger in `Ca^(2+)` mediated hormone, we can follow these steps:

### Step 1: Understand the Concept of Second Messengers
Second messengers are molecules that relay signals received at receptors on the cell surface to target molecules inside the cell. They play a crucial role in various signaling pathways, including those mediated by hormones.

**Hint:** Recall that second messengers amplify the signal from the first messenger (hormone).

### Step 2: Identify the Given Options
The options provided are:
- A. IP3 (Inositol Triphosphate)
- B. DAG (Diacylglycerol)
- C. CAM (Calmodulin)
- D. Phospholipase

**Hint:** List out what each option is known for in the context of cell signaling.

### Step 3: Analyze Each Option
- **IP3 and DAG**: Both are well-known second messengers that are involved in the signaling pathway that leads to the release of calcium ions from the endoplasmic reticulum.

- **CAM (Calmodulin)**: This is a calcium-binding messenger protein that is activated by calcium ions and plays a role in various cellular processes. It is also considered a second messenger in calcium signaling.

- **Phospholipase**: This is an enzyme that catalyzes the hydrolysis of phospholipids. It is not a second messenger itself but rather helps produce second messengers like IP3 and DAG.

**Hint:** Differentiate between second messengers and enzymes that produce them.

### Step 4: Determine the Correct Answer
Since IP3, DAG, and CAM are all involved as second messengers in calcium-mediated hormone signaling, the only option that does not act as a second messenger is phospholipase.

**Final Answer:** The correct option is D. Phospholipase.

### Summary of Steps:
1. Understand the role of second messengers.
2. Identify the options given.
3. Analyze each option based on their function in signaling.
4. Conclude which option does not act as a second messenger.