Purification and Properties of Membrane-Bound Auxin Receptors in Corn

Abstract

Binding sites in corn coleoptile membranes with high affinity for auxins were first detected by Hertel et al. (1). Subsequently we reported evidence for two kinetic classes of auxin binding sites (2,3) and described their solubilization and partial purification (4). Other workers could distinguish only a single kinetic class of binding sites, either in the membrane-bound (5) or solubilized state (6). On the other hand, Dohrmann et al. (7) have suggested that there are three types of auxin-binding sites, two of which have affinities for 1-naphthylacetic acid (NAA) comparable to those reported by ourselves. The third site, which preferentially binds 2,4-dichlorophenoxyacetic acid (2,4-D) and may be an auxin transport site (8), is only revealed under specialized assay conditions.