Question

Which of the following represents the correct sequence of MAP kinase signal transduction pathway?
A. Ras, B. Raf, C. ERK, D. Mek

• A. A B C D
• B. A B D C
• C. A C B D
• D. B A C D

Hint:

Ras $\rightarrow$ Raf (MAPKKK) $\rightarrow$ Mek (MAPKK) $\rightarrow$ ERK (MAPK).

Answer 1

The Correct Option is B

Step 1: Concept
The Mitogen-Activated Protein (MAP) kinase pathway is a highly conserved signaling cascade that communicates signals from receptors to the DNA in the nucleus.

Step 2: Meaning
The pathway involves a series of kinases that phosphorylate and activate the next protein in the chain.

Step 3: Analysis
The canonical sequence begins with the activation of the small G-protein Ras (A). Ras recruits and activates the MAPKKK called Raf (B). Raf then phosphorylates the MAPKK called Mek (D). Finally, Mek phosphorylates and activates the MAPK called ERK (C).

Step 4: Conclusion
The correct linear order of the cascade is Ras $\rightarrow$ Raf $\rightarrow$ Mek $\rightarrow$ ERK. Final Answer: (B)