The Auxin Receptor in Corn Coleoptiles

Abstract

A common approach to isolate hormone receptors is the preparation of a protein fraction with high affinity to a particular hormone. The search for an auxin receptor can be traced back to 1972 when Hertel and his coworkers prepared a membrane fraction with auxin binding activity. In subsequent publications up to three kinetically distinguishable auxin binding sites have been described and thoroughly been characterized (Batt & Venis 1976, Batt et al 1976, Cross & Briggs 1978,1979, Dohrmann et al 1978, Löbler & Klämbt 1985a, Murphy 1980, Ray et al 1977 a/b, Shimomura et al 1986, Tappeser et al 1981, Venis 1977 a/b, 1980). However, the only criterion for an auxin receptor has been its high affinity for auxin, but the data for a signal transduction after auxin binding, leading to a physiological response, was lacking. Indirect evidence for a receptor function of the site I auxin binding was given by the modulation of the auxin binding capacity by light (Walton & Ray 1981). An inhibition of auxin Induced elongation growth by anti receptor antibodies clearly showed the involvement of the auxin receptor in signal transduction (Löbler & Klämbt 1985b).