PARTIAL-PURIFICATION OF GIBBERELLIN-BINDING PROTEINS FROM DWARF PEA

In vitro specific gibberellin binding proteins were obtained from epicotyls of dwarf pea (Pisum sativum L. cv. Progress No.9). The binding was biologically meaningful, i.e., biologically active gibberellins (GAs) such as GA(1) and GA(4) could compete with [H-3]GA(4) binding much more than the biologically inactive GA(4) methyl ester or epi-GA(4). The gibberellin-binding proteins in dwarf pea were partially purified by gel filtration and ion exchange chromatography. The protein fraction eluted by 0.2 M KCl from a DEAE-32 column with a molecular mass estimated to be 40-110 kDa may be the best candidate to contain the cytosolic gibberellin-binding receptor proteins. Specific gibberellin A(4) binding was enhanced about 19 fold by the purification.