Regulation, linkage, and sequence of mouse metallothionein I and II genes.

The mouse metallothionein II (MT-II) gene is located approximately 6 kilobases upstream of the MT-I gene. A comparison of the sequences of mouse MT-I and MT-II genes (as well as those of other mammals) reveals that the coding regions are highly conserved even at "silent" positions but that the noncoding regions and introns are extremely divergent between primates and rodents. There are four blocks of conserved sequences in the promoters of mouse MT-I, mouse MT-II, and human MT-IIA genes; one includes the TATAAA sequence, and another has been implicated in regulation by heavy metals. Mouse MT-I and MT-II mRNAs are induced to approximately the same extent in vivo in response to cadmium, dexamethasone, or lipopolysaccharide. Mouse MT-I and MT-II genes are regulated by metals but not by glucocorticoids after transfection into HeLa cells.