Question

Nuclear Factor Kappa-Light-Chain-Enhancer of Activated B Cells (NF-B) is a protein complex that is found in most animal cells, and it is an important transcription factor that regulates cellular responses to stimuli such as stress hormones, ultraviolet radiation, and pathogens.
The NF-B protein complex is composed of two protein subunits, RelA and p50, and it is inhibited when bound to the IB protein. The action of the NF-B signaling pathway is illustrated in the figure above.
Key:
NF-B protein complex = RelA + p50 proteins
IB$\alpha$ = inhibitory protein
IKK = IB kinase
P = phosphate group
The initiation of this signaling pathway involves

• A. A variety of extracellular signals that bind to cell membrane receptors, which results in the activation the enzyme IB kinase (IKK). The NF-B protein complex is then activated when IB disassociates from it
• B. The NF-B protein complex signaling receptors to activate IB kinase (IKK). NF-B protein complex is then activated when IB disassociates from it
• C. A variety of extracellular signals that bind to cell membrane receptors, which results in the activation of the NF-B protein complex when it becomes phosphorylated
• D. RNA polymerase activation resulting in the expression of the target gene

Answer 1

The correct option is A A variety of extracellular signals that bind to cell membrane receptors, which results in the activation the enzyme IB kinase (IKK). The NF-B protein complex is then activated when IB disassociates from it

Answer is option A i.e. "A variety of extracellular signals that bind to cell membrane receptors, which results in the activation the enzyme IB kinase (IKK). The NF-B protein complex is then activated when IB disassociates from it".
The signal molecules acts as IB protein degradation triggers leading to its degradation by activation of IKK enzyme, which allows the RelA and p50 NF-kappa B dimer to enter the nucleus and activate gene transcription. This signaling pathway helps NF-B to acts as transcription factors that function as dimers and regulate genes involved in immunity, inflammation and cell survival.