A Molecular Kill Switch: How a Human Protein Inherited a Bacterial Weapon
Every cell carries fuel without which it stalls, like an engine with no gasoline. That molecule is NAD+, a carrier of energy and electrons. Bacteria under viral attack have learned to burn this fuel so the virus cannot replicate. It turns out that one of these kill switches, the NIR domain, was handed down to humans as well.
The NIR domain is a part of a protein that works like scissors for NAD+.