A model for the dimeric molecular structure of phytochrome based on small‐angle X‐ray scattering

Abstract

The dimeric molecular structure of pea phytochrome (monomer molecular mass 114 kDa) in the red‐light‐absorbing form was studied with reference to the structures of its molecular domains in a monomer (an N‐terminal 59‐kDa chromophoric domain and a C‐terminal 55‐kDa nonchromophoric domain) using small‐angle X‐ray scattering, and a ‘four‐leaved shape’ model is proposed. The propriety of the model was confirmed by images of the molecule obtained by rotary shadowing electron microscopy.