Q. 26. - Biology

Question

Why is cAMP-mediated signal amplification not required in steroid hormone signaling? Describe how steroid signaling is amplified instead.

Step-by-Step Solution

Answer

There is no amplification in this part of the signalling pathway because the interactions of the signalling molecule with its receptor and the activated receptor with the regulatory region of the target gene are 1-1. 

Step 1: Introduction

The cAMP signalling pathway controls a number of intracellular processes, including cell proliferation, differentiation, and apoptosis, by activating cAMP-dependent protein kinase (PKA).

Step 2: Explanation

In steroid hormone signalling, the hormone directly interacts with the intracellular receptor rather than signalling via a second messenger such as cyclic AMP (cAMP). 

The steroid-receptor complex then enters the nucleus and regulates DNA transcription directly. 

This causes the cell to make multiple copies of the target gene while also amplifying the hormone signal at the transcriptional level rather than the second messenger level.