Figure 3.

Expression regulation of MT gene expression. (A) Schematic representation of human metal response element-binding transcription factor-1 (MTF-1). The regions of the six-zinc fingers (F1–F6), acidic, proline-rich, and serine/threonine-rich domains are indicated by boxes and amino acid numbers; (B) Proposed molecular mechanisms in MT transcription in response to increases of intracellular free zinc. In generic cells, MTF-1 recruits the histone acetyltransferase p300 and increases MT transcription. In MT-repressed cells such as lymphosarcoma cells, and cancer cells, the promoter is highly methylated. DNA methyltransferase (DNMT) and methyl CpG binding proteins (MBD) are involved in the suppression. The epigenetic mechanism is described in Section 4.2. Ac, acetyl group; Me, methyl group; blue circle with two lines, nucleosome.