A method for producing photoactive fusion proteins having a desired activity controllable by far-red and/or near-infrared light, said method comprising the steps of: a. producing at least one DNA molecule encoding one or more homodimeric fusion proteins, each protein comprising: two monomers that each comprise: a photoreceptor module of a bacteriophytochrome; a nucleotidyl cyclase domain capable of being activated upon homodimerization; and a linker sequence between the bacteriophytochrome and the nucleotidyl cyclase domain, wherein the linker sequence comprises an amino acid sequence in multiples of 3 or 4 residues, which corresponds to one, two or more α-helical turns, where one α-helical turn is approximately 3.6 amino acid residues; wherein said monomers are not active when separated, but are capable of combining to form homodimers that are controllable by NIR light; and b. screening said DNA molecule for the ability to produce a homodimeric photoactive fusion protein capable of combining to form homodimers that are controllable by NIR light by a method comprising: i. transforming a designed test non-human organism with said DNA molecule; ii. allowing the expressed fusion protein to bind bacteriophytochrome chromophore and form homodimeric protein; and iii. applying selected wavelengths of NIR light to said transformed organism and determining the level of said desired activity of said fusion protein in said organism in the presence and absence of said selected wavelengths of light; wherein the level of said desired activity of said fusion proteins is controllable by NIR light when the level of said desired activity is changed by the presence and/or absence of NIR light having said selected wavelengths. a. producing at least one DNA molecule encoding one or more homodimeric fusion proteins, each protein comprising: two monomers that each comprise: a photoreceptor module of a bacteriophytochrome; a nucleotidyl cyclase domain capable of being activated upon homodimerization; and a linker sequence between the bacteriophytochrome and the nucleotidyl cyclase domain, wherein the linker sequence comprises an amino acid sequence in multiples of 3 or 4 residues, which corresponds to one, two or more α-helical turns, where one α-helical turn is approximately 3.6 amino acid residues; wherein said monomers are not active when separated, but are capable of combining to form homodimers that are controllable by NIR light; and two monomers that each comprise: a photoreceptor module of a bacteriophytochrome; a nucleotidyl cyclase domain capable of being activated upon homodimerization; and a linker sequence between the bacteriophytochrome and the nucleotidyl cyclase domain, wherein the linker sequence comprises an amino acid sequence in multiples of 3 or 4 residues, which corresponds to one, two or more α-helical turns, where one α-helical turn is approximately 3.6 amino acid residues; wherein said monomers are not active when separated, but are capable of combining to form homodimers that are controllable by NIR light; and a photoreceptor module of a bacteriophytochrome; a nucleotidyl cyclase domain capable of being activated upon homodimerization; and a linker sequence between the bacteriophytochrome and the nucleotidyl cyclase domain, wherein the linker sequence comprises an amino acid sequence in multiples of 3 or 4 residues, which corresponds to one, two or more α-helical turns, where one α-helical turn is approximately 3.6 amino acid residues; b. screening said DNA molecule for the ability to produce a homodimeric photoactive fusion protein capable of combining to form homodimers that are controllable by NIR light by a method comprising: i. transforming a designed test non-human organism with said DNA molecule; ii. allowing the expressed fusion protein to bind bacteriophytochrome chromophore and form homodimeric protein; and iii. applying selected wavelengths of NIR light to said transformed organism and determining the level of said desired activity of said fusion protein in said organism in the presence and absence of said selected wavelengths of light; wherein the level of said desired activity of said fusion proteins is controllable by NIR light when the level of said desired activity is changed by the presence and/or absence of NIR light having said selected wavelengths. i. transforming a designed test non-human organism with said DNA molecule; ii. allowing the expressed fusion protein to bind bacteriophytochrome chromophore and form homodimeric protein; and iii. applying selected wavelengths of NIR light to said transformed organism and determining the level of said desired activity of said fusion protein in said organism in the presence and absence of said selected wavelengths of light;