{PDOC00624}
{PS00782; TFIIB}
{BEGIN}
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* Transcription factor TFIIB repeat signature *
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In eukaryotes the initiation  of  transcription  of protein  encoding genes by
polymerase II is modulated by general and specific transcription factors.  The
general transcription  factors operate through common promoters elements (such
as the TATA box). At  least  seven  different  proteins associates to form the
general  transcription factors:  TFIIA, -IIB, -IID, -IIE, -IIF, -IIG, and -IIH
[1].

Transcription factor IIB (TFIIB) plays a central role in the  transcription of
class II genes,  it  associates  with  a complex of TFIID-IIA bound to DNA (DA
complex) to form a  ternary  complex TFIID-IIA-IBB (DAB complex) which is then
recognized by RNA polymerase II [2,3].  TFIIB is a protein of about 315 to 340
amino acid residues which contains, in its C-terminal part an imperfect repeat
of a domain of about 75 residues.  This  repeat could contribute an element of
symmetry to the folded protein.

The following proteins have been shown to be evolutionary related to TFIIB:

 - An  archaebacterial TFIIB  homolog.  In   Pyrococcus  woesei  a  previously
   undetected  open reading  frame   has  been shown [4] to be  highly related
   to TFIIB.
 - Fungal transcription factor IIIB  70 Kd  subunit  (gene PCF4/TDS4/BRF1) [5].
   This protein  is a general activator  of  RNA polymerase III  transcription
   and plays a role analogous to that of TFIIB in pol III transcription.

As a signature pattern we selected the central section of the repeated domain,
which is the most conserved part of that domain.

-Consensus pattern: G-[KR]-x(3)-[STAGN]-{S}-[LIVMYA]-[GSTA](2)-[CSAV]-[LIVM]-
                    [LIVMFY]-[LIVMA]-[GSA]-[STAC]
-Sequences known to belong to this class detected by the pattern: ALL. In most
 cases this pattern is found twice, except in plants and yeast TFIIB where the
 second copy of the domain is not detected by this pattern.
-Other sequence(s) detected in Swiss-Prot: 2.

-Expert(s) to contact by email:
           Ouzounis C.; ouzounis@ebi.ac.uk

-Last update: April 2006 / Pattern revised.

[ 1] Weinmann R.
     "The basic RNA polymerase II transcriptional machinery."
     Gene Expr. 2:81-91(1992).
     PubMed=1633439
[ 2] Hawley D.
     "Transcriptional activation: enter TFIIB."
     Trends Biochem. Sci. 16:317-318(1991).
     PubMed=1949150
[ 3] Ha I., Lane W.S., Reinberg D.
     "Cloning of a human gene encoding the general transcription initiation
     factor IIB."
     Nature 352:689-695(1991).
     PubMed=1876184; DOI=10.1038/352689a0
[ 4] Ouzounis C., Sander C.
     "TFIIB, an evolutionary link between the transcription machineries of
     archaebacteria and eukaryotes."
     Cell 71:189-190(1992).
     PubMed=1423586
[ 5] Khoo B., Brophy B., Jackson S.P.
     "Conserved functional domains of the RNA polymerase III general
     transcription factor BRF."
     Genes Dev. 8:2879-2890(1994).
     PubMed=7995525

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