Auxin-binding protein from coleoptile membranes of corn (Zea mays L.). II. Localization of a putative auxin receptor.

With the aid of affinity chromatography on auxin-binding protein-Sepharose (ABP-Sepharose) monospecific IgGanti-ABP from rabbit antisera were isolated as judged by immuno-double diffusion test and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. With this IgGanti-ABP the ABP is localized within the outer epidermal cells of coleoptiles using indirect immunofluorescence labeling. Auxin-induced growth of coleoptile segments can be inhibited by IgGanti-ABP, and the auxin response of split coleoptile sections is also strongly reduced by IgGanti-ABP. The ABP, therefore, is referred to as an auxin receptor. This auxin receptor is localized at the plasmalemma of the outer epidermal cells of the coleoptile.