Definition: Anatoxin is a protein found in various bacteria, acting as an endoplasmic reticulum (ER) stress inducer. It inhibits cellular proteins involved in ER integrity, leading to membrane disruption and potentially toxic effects on host cells. Definition: Anatoxin is an endoplasmic reticulum stress-inducing protein that activates the proteasome in bacteria to degrade proteins involved in ER integrity, thereby contributing to cell death.