Question

How does NF-κB induce gene expression?

a. A small, hydrophobic ligand binds to NF-κB, activating it.

b. Phosphorylation of the inhibitor Iκ-B dissociates the complex between it and NF-κB, and allows NF- κB to enter the nucleus and stimulate transcription.

c. NF-κB is phosphorylated and is then free to enter the nucleus and bind DNA.

d. NF-κB is a kinase that phosphorylates a transcription factor that binds DNA and promotes protein production.

Short answer

The correct answer is option b - Phosphorylation of the inhibitor Iκ-B dissociates the complex between it and NF-κB, and allows NF- κB to enter the nucleus and stimulate transcription.

Step-by-step solution

Introduction

Signal transduction

• It is also known as cell signaling.
• The transmission of chemical signals from the exterior to the interior of a cell is known as signal transduction.
• Receptors in the plasma membrane use signal transduction pathways to have a variety of impacts on the cell.
• Signaling pathways provide a wide range of outcomes, depending on the type of cell involved as well as external and internal factors.

Explanation

The correct answer is option b.

• The protein complex NF-κB(nuclear factor kappa-light-chain-enhancer of activated B cells) regulates DNA transcription.

• The protein complex NF-κB cannot enter the nucleus of the cell when Iκ-B is coupled to NF-κB, but when Iκ-B is phosphorylated by PKC, it can no longer bind to NF-κB, allowing NF-κB(a transcription factor) to enter the nucleus and commence RNA transcription. In this scenario, phosphorylation has the effect of inactivating an inhibitor and therefore activating the transcription process.