| Type: | Family | Name: | SAS complex subunit SAS5/transcription initiation factor TFIID subunit 14 |
| Description: | This entry represents the Sas5 (Something About Silencing 5) subunit from the SAS complex, as well as subunit 14 (TAF14) from transcription initiation factor IID.The native yeast SAS complex is a trimeric acetyltransferase complex composed of Sas2, Sas4, and Sas5. Sas2 is a member of the MYST protein family of histone acetyltransferases (HATs) []. Sas5 is required for maximal histone acetyltransferase (HAT) activity of the complex, suggesting that it may be required to stabilise the complex or help in substrate recognition. SAS is capable of acetylating both free histones and nucleosomes, and is required for both histone H4 lysine-16 acetylation and histone H3 lysine-14 acetylation. This specific lysine preference corresponds to the role of SAS complex in antagonizing the spreading of Sir proteins at silent loci in Saccharomyces cerevisiae(Baker's yeast). The SAS complex is involved in transcriptional silencing at telomeres and at HML locus, as well as being involved in rDNA silencing. TAF14 functions as a component of the DNA-binding general transcription factor complex TFIID, the RNA polymerase II associated general transcription factor complex TFIIF, and the chromatin-remodeling complex SWI/SNF. Binding of TFIID to a promoter (with or without TATA element) is the initial step in pre-initiation complex (PIC) formation. TFIID plays a key role in the regulation of gene expression by RNA polymerase II through different activities such as transcription activator interaction, core promoter recognition and selectivity, TFIIA and TFIIB interaction, chromatin modification (histone acetylation by TAF1), facilitation of DNA opening and initiation of transcription. TFIIF is essential for the initiation of transcription by RNA polymerase II. TFIIF functions include the recruitment of RNA polymerase II to the promoter bound DNA-TBP-TFIIB complex, decreasing the affinity of RNA polymerase II for non-specific DNA, allowing for the subsequent recruitment of TFIIE and TFIIH, and facilitating RNA polymerase II elongation. The TAF14 subunit has stimulatory activity. TAF14 is also a component of the SWI/SNF complex, an ATP-dependent chromatin-remodelling complex that is required for the positive and negative regulation of gene expression of a large number of genes. | Short Name: | Sas5/TAF14 |
