General transcription factors GTFs

RNA polymerases interact with unique cw-active regions of genes, termed promoters, in order to form preinitiation complexes (PICs) capable of initiation. In eukaryotes the process of PIC formation is facilitated by multiple general transcription factors (GTFs), TFIIA, B, D, E, F, and H. 

General transcription factors (GTFs) that bind to eukaryotic promoters are functionally analogous to a factor in prokaryotes. 

General transcription factors (GTFs) help to localize the RNA polymerase correctly on the promotor and to form a transcription-competent initiation complex. They serve to impose a specific structure on the transcription start site, and some of them are required for elongation of the transcript. 

Transcription initiation begins by the formation of a preinitiation complex, and most of the control of transcription occurs at this step. This complex normally contains RNA polymerase II and six general transcription factors (GTFs)—TTHA, TFIIB, TTIID, TFIIE, TFIIF, and TFIIH. 

The general transcription factors are required for all promoters. Much work is still going on to determine the structure and function of each of the parts of the preinitiation complex. Each GTF has a specific function, and each is added to the complex in a defined order. Table 11.3 is a summary of the components of the preinitiation complex. 

Purification of general transcription factors, especiaUy TBP, has to be carried out at the maximum possible rate to prevent protein aggr ation over time. Concentration of GTFs can be performed only in a stirred cell to prevent formadon... 

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