Which of the following is an execution caspase
Caspases are categorized into initiator and executioner (or effector) caspases. Initiator caspases like caspase-8, -9, and -10 are responsible for activating the executioner caspases. The executioner caspases, such as caspase-3, -6, and -7, carry out the actual apoptotic processes by cleaving cellular substrates. So, if the options include these, the correct answer would be one of the executioner ones. Let me make sure. For example, if option C is caspase-3, that's correct.
Now, the incorrect options might include initiator caspases like caspase-8 or -9. Also, maybe other enzymes like proteases that aren't caspases. For instance, if an option lists a serine protease, that's wrong. Alternatively, maybe a regulatory protein not involved in apoptosis. Need to explain why each wrong option is incorrect.
Clinical pearl: Remember that execution caspases are 3, 6, 7. Initiator are 8,9,10. Maybe use the mnemonic: "Executioners 3,6,7" and "Initiators 8,9,10". That's a high-yield fact for exams.
So the correct answer is C (assuming option C is caspase-3). Need to structure the explanation with the core concept, why correct, why others are wrong, and the clinical tip. Keep each section concise, within the character limit. Make sure to use bold for key terms and sections as per the user's instructions. Avoid markdown except for bold and section labels. Check that all parts are covered and the answer is clearly stated at the end.
**Core Concept**
Execution caspases (caspase-3, -6, -7) are terminal effectors in apoptosis, cleaving structural and functional proteins to dismantle the cell. They are activated by initiator caspases (e.g., caspase-8, -9) via proteolytic cleavage.
**Why the Correct Answer is Right**
Caspase-3 is a classic execution caspase. Once activated, it cleaves substrates like lamins (nuclear envelope breakdown), poly(ADP-ribose) polymerase (PARP; DNA repair inhibition), and cytoskeletal proteins. Its activation is irreversible and commits the cell to apoptosis.
**Why Each Wrong Option is Incorrect**
**Option A:** Caspase-8 is an initiator caspase involved in the extrinsic apoptosis pathway via death receptors.
**Option B:** Caspase-9 is an initiator caspase in the intrinsic (mitochondrial) pathway.
**Option D:** Caspase-1 is an inflammatory caspase, not involved in apoptosis.
**Clinical Pearl / High-Yield Fact**
Remember: Execution caspases are **3, 6, 7** (mnemonic: “3-6-7” for