Photoactive yellow protein
In molecular biology, the PYP domain is a p-coumaric acid-binding protein domain. They are present in various proteins in bacteria.
PYP is a highly soluble globular protein with an alpha/beta fold structure. It is a member of the PAS domain superfamily, which also contains a variety of other kinds of photosensory proteins.
PYP was first discovered in 1985.
A recently developed chemogenetic system named FAST was engineered from PYP to specifically and reversibly bind a series of hydroxybenzylidene rhodanine derivatives for their fluorogenic properties. Upon interaction with FAST, the fluorogen is locked into a fluorescent conformation unlike when in solution. This new protein labelling system is used in a variety of microscopy and cytometry setups.
