A researcher measures enzymatic activity in cells undergoing apoptosis and finds maximal cleavage activity against the substrate DEVD, producing characteristic cellular fragmentation. The enzyme responsible belongs to which functional class of caspases?

• A Inflammatory caspases
• B Initiator caspases
• C Executioner caspases ✓
• D Granzyme B homologues

Explanation

Caspase-3, the dominant executioner caspase, recognizes the tetrapeptide DEVD and cleaves numerous cellular substrates including structural nuclear lamins, cytoskeletal proteins, and endonuclease inhibitors such as iCAD, producing DNA fragmentation and apoptotic body formation. Initiator caspases (caspase-8 and caspase-9) have long prodomains containing death folds and activate executioners rather than cleaving DEVD substrates themselves. Inflammatory caspases such as caspase-1 mediate IL-1 processing in pyroptosis.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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