Abrus precatorius (rosary pea) seeds contain abrin, a ribosome-inactivating protein. At a cellular level, abrin causes cell death by:

• A Blocking voltage-gated calcium channels in myocardial cells
• B Inhibiting DNA topoisomerase II, causing double-strand breaks
• C Chelating cytoplasmic zinc ions and disrupting metalloprotease activity
• D Depurinating a specific adenosine residue in 28S rRNA, halting protein synthesis ✓

Explanation

Abrin is a type-II ribosome-inactivating protein (RIP) structurally similar to ricin. Its A-chain is an N-glycosidase that depurinates a specific adenosine residue (A4324 in rat) within the sarcin-ricin loop of 28S rRNA. This irreversibly inactivates the ribosome and halts elongation factor binding, completely arresting protein synthesis and triggering cell death. The B-chain is a lectin that facilitates cell entry. The mechanism distinguishes it from channel blockers, topoisomerase inhibitors, and chelators.

Reference: The Essentials of Forensic Medicine and Toxicology (Narayan Reddy), 34th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.