Consider the following
1. AdenylCyclase
2. Inosital 1, 4, 5-triphosphate
3. cAMP
4. Catecholamine
Which of the above is/are second messengers ?

Options

A. 1, 3 and 4
B. 2 and 3 only
C. 1 and 3 only
D. 1, 2, 3 and 4

Answer

To determine which of the given options are second messengers, let's analyze each one step by step.

### Step 1: Understand the concept of second messengers
Second messengers are intracellular signaling molecules released by the cell in response to exposure to extracellular signaling molecules (first messengers). They help transmit signals from receptors on the cell surface to target molecules inside the cell, leading to a physiological response.

**Hint:** Remember that second messengers are generated in response to first messengers and play a crucial role in signal transduction.

### Step 2: Analyze Adenyl Cyclase
Adenyl cyclase is an enzyme that converts ATP to cyclic AMP (cAMP). While it plays a crucial role in the signaling pathway, it is not itself a second messenger. Instead, it is responsible for synthesizing one.

**Hint:** Focus on the function of adenyl cyclase; it is an enzyme, not a signaling molecule.

### Step 3: Analyze Inositol 1, 4, 5-triphosphate (IP3)
Inositol 1, 4, 5-triphosphate is a second messenger involved in the signaling pathways of various hormones and neurotransmitters. It facilitates the release of calcium ions from intracellular stores, which is essential for many cellular processes.

**Hint:** Consider the role of IP3 in calcium release; it is a key player in signal transduction.

### Step 4: Analyze Cyclic AMP (cAMP)
Cyclic AMP is a well-known second messenger that is generated from ATP by the action of adenyl cyclase. It plays a significant role in various physiological responses, including metabolism and cell growth.

**Hint:** Recall that cAMP is directly involved in transmitting signals within the cell.

### Step 5: Analyze Catecholamine
Catecholamines are hormones (such as adrenaline) produced by the adrenal glands and act as first messengers. They are involved in the body’s response to stress but do not function as second messengers.

**Hint:** Remember that catecholamines are hormones that initiate a response but do not transmit signals within the cell.

### Conclusion
Based on the analysis:
- **Adenyl Cyclase**: Not a second messenger (it synthesizes cAMP).
- **Inositol 1, 4, 5-triphosphate**: Is a second messenger.
- **Cyclic AMP (cAMP)**: Is a second messenger.
- **Catecholamine**: Not a second messenger (it is a hormone).

Thus, the second messengers from the options provided are **Inositol 1, 4, 5-triphosphate and Cyclic AMP (cAMP)**.

**Final Answer:** 2 and 3 are second messengers.