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General Comment |
Eukaryotic transcription and mRNA synthesis are complex biochemical processes controlled in part by the concerted action
of a set of general transcription factors that regulate the activity of RNA polymerase II at both the initiation and
elongation stages of transcription. Aso et al. (1995) noted that several general initiation factors, including TFIIA, TFIIB, TFIID, TFIIE, and TFIIH, and several accessory
proteins (e.g., TAFs), have been identified in eukaryotic cells and found to promote selective binding of RNA
polymerase II to promoters and to support a basal level of transcription.
In addition to the general initiation factors, 3 general elongation factors, SII, TFIIF, and elongin (SIII), have been
defined biochemically in eukaryotes and shown to increase the overall rate at which RNA polymerase II transcribes duplex
DNA. TFIIF from higher eukaryotes is a heterodimer composed of RAP74, a subunit of approximately 70 kD and
RAP30, a subunit of approximately 30 kD. Elongin (also referred to as SIII) is a heterotrimer composed of A
(TCEB3), B, and C subunits of 110, 18, and 15 kD, respectively. The complex activates elongation of
mammalian RNA polymerase II by suppressing transient pausing of the polymerase at many sites within transcription units.
NCBI Summary:
This gene encodes the protein elongin A, which is a subunit of the transcription factor B (SIII) complex. The SIII complex is composed of elongins A/A2, B and C. It activates elongation by RNA polymerase II by suppressing transient pausing of the polymerase at many sites within transcription units. Elongin A functions as the transcriptionally active component of the SIII complex, whereas elongins B and C are regulatory subunits. Elongin A2 is specifically expressed in the testis, and capable of forming a stable complex with elongins B and C. The von Hippel-Lindau tumor suppressor protein binds to elongins B and C, and thereby inhibits transcription elongation.
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