Article (han_haem_2007)
Han, Y.; Meyer, M. H. F.; Keusgen, M. & Klug, G.
A haem cofactor is required for redox and light signalling by the AppA protein of Rhodobacter sphaeroides
Molecular microbiology, 2007, 64, 1090-104

Article (jger_appa_2007)
Jäger, A.; Braatsch, S.; Haberzettl, K.; Metz, S.; Osterloh, L.; Han, Y. & Klug, G.
The AppA and PpsR proteins from Rhodobacter sphaeroides can establish a redox-dependent signal chain but fail to transmit blue-light signals in other bacteria
Journal of bacteriology, 2007, 189, 2274-82