PiXELLs are condensates that dissociate upon blue light stimulation. The basic module consists of the algal-derived Pix proteins. PixD forms dimers and PixE is a monomer. When expressed together they associate in large complexes of a 10:5 or 10:4 ratio. Fusing these nucleating proteins to sticky IDRs drives their condensation.
Other optogenetic condensates system that phase separates upon blue light exposure is called optoDroplets, Corelets and CasDrop.
+ common molecular grammar of IDR
+ IDR subunit is highly tunable
+ optogenetic control
- large constructs
- potential interference with endogenous processes depending on IDR
- prolonged blue light exposure is toxic in mammalian cell models
- two-component system