Gene transcriptions/Elements/Metal responsives

Metal responsive elements (MRE)s, or TGC boxes, may occur in the core promoter of some human DNA genes.

TGC boxes
Notation: let the symbol MT stand for metallothionein.

"The metallothionein (MT) genes provide a good example of eucaryotic promoter architecture. MT genes specify the synthesis of low-molecular-weight metal-binding proteins. They are transcriptionally regulated by the metal ions cadmium and zinc (11), glucocorticoid hormones (18), interferon (14), interleukin-1 (22), and tumor promoters (2). The metal ion regulation of MTs is conferred by a short sequence element called the metal-responsive element (MRE [21]) or TGC box (31, 34), which functions as a metal ion-dependent enhancer."

Consensus sequences
"The promoter regulatory sequences are identified by homology to published GRE (21), MRE (35), and GC box (15) consensus sequences."

Here "is a consensus sequence for the MREs of the rat MT-1 gene." In the direction of transcription on the DNA template strand: 3'-CNNTGCRCYCGGGNC-5', where R = purine; Y = pyrimidine; and N = any nucleotide (nt).

"[T]hree potential metal response elements (MREs) [overlap] the E-boxes in the repeats, (TGCACGT with TGCRCNC being the consensus sequence; 17,18)."

The reproducible consensus sequence seems to be 3'-TGCRCNC-5', specifically 3'-TGC(A/G)CNC-5'.

MREs
Six MREs lie in the proximal promoter of the rat MT-1 gene upstream of the TATA box to almost -200 nts from the transcription start site.

Hypotheses

 * 1) At least two human gene isoforms have their transcription initiated by an MRE.