Following mitochondrial outer membrane permeabilization, cytochrome c enters the cytosol and binds a scaffolding protein, triggering formation of a heptameric complex in the presence of dATP. This complex recruits and activates a specific procaspase. The complex and its recruited caspase are:

• A Death-inducing signaling complex recruiting procaspase-8
• B Inflammasome composed of NLRP3 recruiting procaspase-1
• C Apoptosome composed of Apaf-1 recruiting procaspase-9 ✓
• D PIDDosome recruiting procaspase-2

Explanation

Cytochrome c binds Apaf-1 (apoptosis-activating factor 1) in the cytosol; with dATP, Apaf-1 oligomerizes into the heptameric apoptosome, which recruits procaspase-9 via CARD-CARD interactions, producing active caspase-9 that cleaves executioner caspases 3 and 7. The DISC (option A) belongs to the death receptor pathway and forms at the plasma membrane, not the cytosol, and uses caspase-8. The NLRP3 inflammasome activates caspase-1 for IL-1beta processing and pyroptosis, not apoptotic execution.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.