These findings provide a platform for the study of direct gene-environment interactions. However, the important missing piece is the identification of the relevant DNA target. We assumed that a potential target for regulation is the regulatory region of the GR gene. Regulatory regions contains sequences that alter the activity of the gene, such as promoters or suppressors, and are commonly found in front (or upstream) of the coding region of the gene that actually produces the protein. We identified and characterized several new GR mRNAs cloned from rat hippocampus (Figure 2).83 All mRNAs encode a common protein, but differ in their 5 '-leader sequences presumably as a consequence of alternative splicing of, potentially, several different sequences from the 5' noncoding exon 1 region of the GR gene. In this case, the variation in the mRNAs reflects the different promoters that are spliced onto the coding region during transcription to create diverse GR mRNAs. The promoter, while spliced onto the mRNA, does not alter the translational phase by which mRNA is “translated” into the amino acid sequence that defines the protein
