- 5'-Azido-[3,6-3H2]-1-napthylphthalamic acid, a photoactivatable probe for naphthylphthalamic acid receptor proteins from higher plants: identification of a 23-kDa protein from maize coleoptile plasma membranes. Zettl, R., Feldwisch, J., Boland, W., Schell, J., Palme, K. Proc. Natl. Acad. Sci. U.S.A. (1992)