A typical plant gene has the following region beginning with the 5'end:

i). Promoter: For transcription initiation

ii). Enhancer/silencer: Concerned with regulation of gene

iii). Transcriptional start site or cap site: From here initiation of transcription take place

iv). Leader sequence: It is untranslated region

v). Initiation codon

vi). Exons

vii). Introns

viii). The stop codon

ix). A second untranslated region, and

x). Poly A tail

Figure 25.1: A typical plant gene

Promoter is a region of DNA sequence which helps in the transcription of a particular gene. This contains specific DNA sequences as well as response elements which provide a secure initial binding site for RNA polymerase. These proteins called transcription factors that recruit RNA polymerase. The CAAT and TATA boxes represent consensus sequences within promoter for RNA polymerase II. ATG (AUG in mRNA) is initiation codon for mRNA translation, and mark the beginning of coding sequence of the gene. A sequence between the cap site and ATG is not translated and form the 5'-leader sequence of mRNA. Codon TAG/TAA/TGA are chain terminating codon and it is followed by a stretch of nontranslated region. At the end, poly-adenylation site is present which denotes the end of transcription.