R. Meyer et Ia. Dubery, HIGH-AFFINITY BINDING OF A PROTEIN-LIPOPOLYSACCHARIDE PHYTOTOXIN FROMVERTICILLIUM-DAHLIAE TO COTTON MEMBRANES, FEBS letters, 335(2), 1993, pp. 203-206
The presence of a specific binding site for a protein-lipopolysacchari
de (PLP) phytotoxin isolated from culture filtrates of Verticillium da
hliae has been demonstrated in plasma membranes from cotton seedlings.
The I-125-labelled PLP was used as a ligand in binding assays with pl
asma membrane enriched fractions. Root tissue exhibited the highest am
ount of binding activity compared to hypocotyl and cotyledon tissue. B
inding of the [I-125]PLP was saturable, reversible, and with an affini
ty (K-d = 1.42 X 10(-8)M) comparable with the concentration required f
or biological activity. A single class of binding site was found, and
the maximal number of binding sites were estimated as 5.4 x 10(-15) mo
l/mu g protein.