[Campbell Biology P.271] Based on Figure 11.10 and its legend, what would be the most likely... | Practice Question

Based on Figure 11.10 and its legend, what would be the most likely consequence if a mutation in protein kinase 2 made it incapable of being phosphorylated?

  • A: The cellular response would be continuously active.
  • B: Protein kinase 1 would remain inactive.
  • C: The phosphorylation cascade would be interrupted at protein kinase 2, preventing the cellular response.
  • D: Protein phosphatases would become hyperactive.

Explanation

Figure 11.10 shows that inactive protein kinase 2 is activated by phosphorylation by active protein kinase 1. If protein kinase 2 cannot be phosphorylated, it will remain inactive, thus halting the phosphorylation cascade at this step and preventing the subsequent phosphorylation of the active protein purple and the resulting cellular response.