METALLOTHIONEIN-LIKE PROTEIN IN THE HEPATIC CYTOSOL OF THE TERM RAT FETUS

Endogenous zinc levels in the cytosol of normal fetal rat liver were found to be 4.5- to 7-fold higher than levels found in the cytosol of the corresponding maternal liver. When the fetal cytosol was subjected to gel-filtration, 50 to 60% of the zinc was found to be associated with a peak not present in maternal cytosol. In vitro addition of CdCl2 to fetal cytosol prior to gel-filtration caused a displacement of zinc from the peak and an accumulation of cadmium. Pretreatment of the pregnant female with CdCl2 48 hr prior to term led to the appearance of a peak in the maternal hepatic cytosol with an elution volume similar to the fetal peak. The peak contained both cadmium and zinc which is characteristic of metallothionein. The results suggest the presence of a metallothionein-like protein in the cytosol of term fetal liver which is not normally found in maternal liver and which appears to function as a storage depot for endogenous zinc. © 1979 Academic Press, Inc. All rights reserved.