A Review on Characterization of Zein Multigene Family and its Regulatory Elements

Maize (Zea mays) is one of the most productive crops in the world. Corn seeds, in particular, are attractive for a variety of reasons, including ease of storage and transportation, and the ability to store proteins stably for a long time and are easy to process (Howard and Hood, 2005). Maize is also a common food source for humans and animals, making it a convenient container for biopharmaceuticals that contain orally administered products. The growing prevalence of transgenes in crop improvement and biopharmaceuticals requires the exploration of ways to regulate transgene expression. Regulation can occur indifferent stages of gene expression and may be particularly important during transcription. Promoters that drive transgene expression provide this control. Promoters are regions of DNA upstream of the coding region of the gene which contains specific sequences recognized by proteins involved in transcription initiation. Transcription initiation for most protein-coding genes involves the binding and activation of RNA polymerase II. Variation in gene expression occur when other distinct, semi-conserved sequence elements are present in the regulatory regions of the gene, usually upstream or 5’ of the RNA polymerase binding site. These elements bind to protein factors involved in controlling the level and pattern of gene expression. The availability of a wide range of promoters that differ in their ability to regulate the temporal and spatial patterns of transgene expression could significant increase in the success of the application of transgenic technology. Studies on the regulatory elements of genes encoding key regulatory enzymes in the starch biosynthetic pathway and genes encoding storage proteins will be useful to find promoters and highly expressed compounds.