Ribosome-Inactivating Protein (RIP)
Definition
A glycoprotein toxin that enzymatically depurinates 28S rRNA and shuts down protein synthesis. Abrin (Abrus precatorius) and ricin (Ricinus communis) are type 2 RIPs and are lethal in microgram quantities by parenteral routes.
- Mechanism
- Depurinates 28S rRNA, halting protein synthesis
- Class
- Type 2 RIP
- Examples
- Ricin and abrin
- Lethal dose route
- Microgram quantities, parenteral exposure
Common questions
How do type 2 RIPs like ricin differ from type 1 RIPs?+
Type 2 RIPs such as ricin and abrin carry an extra lectin B-chain that binds cell-surface receptors and lets the toxic A-chain enter cells, making them far more lethal than type 1 RIPs, which lack this binding chain and are largely non-toxic to intact cells.
Why is detecting ricin or abrin poisoning analytically difficult?+
Both toxins act catalytically at very low doses and are cleared or bound within cells quickly, so detection generally relies on identifying ricinine or abrine markers, or immunoassay and mass spectrometry methods, rather than finding the intact protein itself.
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