β-Glucan elicitor-binding protein
A high-affinity membrane-bound β-glucan elicitor-binding protein has been purified from microsomal preparations of French bean (Phaseolus vulgaris L.) roots. A 5900-fold purification was achieved by affinity chromatography of functionally solubilized membrane proteins. The β-glucan-binding protein had an apparent molecular mass of 78 kDa when subjected to SDS-PAGE. Western blot analysis showed specific crossreactivity of this French bean protein with an antiserum raised against a synthetic peptide representing an internal 15 amino acid fragment of the β-glucan-binding protein from soybean. Northern blot analysis with a cDNA probe of the soybean β-glucan-binding protein gene revealed a crosshybridizing transcript of 2.4 kb in French bean. These results indicate that the β-glucan-binding proteins of French bean and soybean are conserved homologs involved in β-glucan elicitor recognition.