Phytochromes: Structure, Function & Mechanisms of action

#plants #phytochromes #photoreceptors #chromoproteins #plantphysiology #mscbotany
Phytochromes are photoreceptors that respond to environmental light conditions. Phytochromes are dimeric chromoproteins with each monomer possessing a covalently linked open tetrapyrrole phytochromobilin as a chromophore.
In higher plants, phytochromes are encoded by small gene families, for example, five members (phyA to phyE) in Arabidopsis thaliana.
They are further classified into
light-labile type I (phyA) and
light-stable type II (phyB to phyE) species.
Phytochrome occurs as a dimer made up of two subunits, each with molecular mass of 125 kDa.
Each subunit consists of two components:
light- absorbing pigment molecule, chromophore and
a polypeptide chain, apo protein...