“NanoBiT® and NanoBRET™ technologies provide the sensitivity necessary to detect protein:protein interactions at the concentrations expressed in vivo. Both are bioluminescence-based methods that are particularly useful in viral studies due to the small size and bright signal of the luciferase used.”
Here’s an article at MIT’s website.
Here’s the wiki article on Luciferase.
It’s almost as if the Divine Providence is leaving a trail of breadcrumbs, or even beating humanity over the head with a two-by-four so that no one will be able to say, “But I didn’t KNOW!!!”