Isolation and partial characterization of a non-thionein, zinc-binding protein from the liver of rainbow trout (Salmo gairdneri).

A Zn-binding protein (ZBP) was induced in the liver of Donaldson strain rainbow trout by 7 mg/kg i.p. injections of divalent Zn ions. ZBP synthesis was inhibited (74%) by cycloheximide. ZBP had a minimum molecular weight of 16,900 and was composed of two subunits with apparent molecular weights of 9650 and 6050. Purified ZBP contained 4% phenylalanine, 4% isoleucine, 5-6% leucine and 3.48% Zn. Each protein molecule bound nine Zn atoms and contained at least four sulfhydryl groups. Molecular weight, two subunits and the presence of aromatic amino acids suggested that ZBP was not metallothionein.