Factors regulating the transcription of eukaryotic protein coding genes and their mechanism of action—A review.

ABSTRACT

Protein factors play a crucial role in establishing gene-specific and cell-specific regulation of the process of transcription. These include general transcription factors which recognize TATA and CCAAT boxes and which form components of the RNA polymerase II system. Specific transcription factors interact with characteristic promoter elements of individual genes. Some of the examples are SP1, glucocorticoid receptor, GCN4, GAL4 and many others. Transcription factors have a DNA binding domain demarcated from the transcription activation domain. Some factors may have an additional ligand (small molecule) binding domain. Typical structural features such as helix-turn-helix motif, zinc finger and leucine zipper have been recognized in the DNA binding domain of the transcription factors. The acidic domain of the protein factors is involved in the transcription activation process. It appears that activation is the result of the combined action of several regulatory proteins binding at different regions of the promoter. Interaction between proteins bound to DNA but seperated by long stretches of nucleotides is facilitated by DNA bending. Functional specificity as well as diversity are feasible with a limited number of transcription factors through alterations in the architecture of interaction between a group of proteins bound to promoter elements.