phyB missense mutations fall into two functional categories.

Residues are classified according to the impact the substitution has on the capacity of the phyB molecule to covalently attach the chromophore and undergo normal photoreversible interconversion between the Pr and Pfr conformers. Class I: Fails to ligate chromophore and/or fails to undergo normal photoconversion. Class II: Undergoes normal photoconversion, but fails to bind PIF3. (+) = normal activity. (−) = absence of normal activity. The location of each residue within the three dimensional structure is indicated.
1Undergoes photoconversion, but Pfr form is spectrally aberrant (see Figure S2).