Transcription initiation factors

Roy, A. L., Meisteremst, M., Pognonec, P., and Roeder, R. G. (1991). Cooperative interaction of an initiator-binding transcription initiation factor and helix-loop-helix activator USF. Nature 354 245-248. 

Because of the preceding properties, our profile procedure appears to produce highly sensitive and specific common pattern representations from limited numbers of defining sequences compared with other current methods (Figs. 5 and 7). This was shown by the construction of such profiles from more than 50 completely unrelated functional families. In more than 90% of the families, the sensitivity and specificity are more than 98%. This is also supported by the repeated sampling study of the complex bacterial transcription initiation factors. Finally, these methods allow for the localized recognition of entire domains within multidomain structures, as seen in Fig. 6. 

The purification and structural and functional characterization of the general initiation factors has proven extremely difficult. The specific function of the various factors, as well as their structural role in the entire complex, remains poorly resolved. According to the current model, the general transcription initiation factors, with which an exact start of transcription is possible in vitro, are required for the formation of a basal... 

A transcription-competent pre-initiation complex consisting of general transcription initiation factors and RNA polymerase II, can be reconstituted in the test tube from the individual components. As outlined in Fig. 1.31, efficient reconstitution requires a defined order for the addition of the individual components. 

The general transcription initiation factors can be assigned the role fulfilled by a single protein in procaryotes-namely the o-factor. This role includes the correct positioning of the RNA polymerase on the promoter and the preparation for the incorporation of the first nucleotide. 

General transcription initiation factors TFIIB, TFIIE, TFIIF and TFIIH have been identified as components of the RNA polymerase 11 holoenzyme of yeast. Various forms of the yeast holoenzyme contain further proteins, known as mediators or SRB proteins (SRB, suppressor of RNA polymerase B). The mediators fimction as coactivators (see 1.4.3.2). The holoenzyme is difficult to define structurally because the proteins accessory to the core enzyme (see table 1) may not be permanently associated with RNA polymerase II. 

The TATA binding protein and general transcription initiation factors. A slow basal level of transcription can be observed when all but a small part of the control region at the 5 end of a gene is deleted.325 This minimum promoter, which includes the TATA sequence, is the binding site of both the RNA... 

Transcription initiation factor IIIB, isoform 3 Human (None) (None) (None)... 

Kassavetis, G. A., Braun, B. R., Nguyen, L. H., and Geiduschek, E. P. (1990). S. cerevisiae TFIIIB is the transcription initiation factor proper of RNA polymerase III, while TFIIIA and TFIIIC are assembly factors. Cell 60, 235-245. 

TABLE 13.5 Human general transcription initiation factors for RNA polymerase II... 

---