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While searching for ‘organ-specific’ genes in pea ( Pisum sativum L.) we have isolated a gene (designated PsMT A ) which has an ORF encoding a predicted protein with some similarity to metallothioneins (MTs). The PsMT A transcript is abundant in roots which have not been exposed to elevated concentrations of trace metals.

The pea (Pisum sativum L) genePsMTA has an ORF encoding a predicted protein with sequence similarity to class I metallothioneins (MTs). To examine the metal-binding properties of the PsMTA protein it has been expressed inE. coli as a car☐yterminal extension of glutathione-S-transferase (GST). Metal ions were associated with the expressed protein when purified from lysates ofE. coli grown in metal supplemented media. The pH of half-dissociation of Zn, Cd and Cu ions from the recombinant fusion protein was determined to be 5.35, 3.95 and 1.45 respectively, compared with equivalent estimates of 4.50, 3.00 and 1.80 for equine renal MT.