Metallothionein-like proteins in human placenta and fetal membranes.

Metallothionein (MT) levels were measured in the term human placenta, chorion, and amnion by the Cd-radioassay method. MT concentrations in the amnion and chorion were 8 to 9 micrograms MT/g tissue while placental levels were approximately half this value. For individual subjects a significant correlation (r2 = 0.96) was found for placental and chorionic MT, while amnionic MT levels did not correlate with either placental or chorionic MT. Gel filtration and uv spectral analysis confirmed the presence of a MT-like protein in cytosol obtained from amnion, chorion, and placenta. MT levels in trophoblasts cultured from chorion were increased upon exposure in vitro to either Cd or Zn.