Sensory rhodopsins are seven-helical transmembrane proteins that play a fundamental role in the life of the archaea. Archeabacterial phototaxis is governed by the two different photoreceptors: sensory rhodopsin I and II. They enable bacteria to successfully navigate to seek optimal light conditions and avoid harmful UV radiation. Due to extreme difficulty in crystallizing transmembrane proteins, the determination of a high resolution structure of this two-component signal system using x-ray crystallography has been partially successful. Here we propose to use neutron specular reflectometry (NR), off - specular and grazing incidence small angle scattering (GISANS) to complement previous SAS measurements in order to reconstruct protein structure with help of computer modeling. Subsequently, we will illuminate the sensory rhodopsin II (NpSRII)/cognate transducer (NpHtrII) complex with a light to determine the activated protein structure. The latter cannot be studied with x-ray crystallography due to the steric limitations of conformational changes when the protein transforms from a native to an activated state.