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TIF‐IC, a factor involved in both transcription initiation and elongation of RNA polymerase I.
Author(s) -
Schnapp G.,
Schnapp A.,
Rosenbauer H.,
Grummt I.
Publication year - 1994
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1994.tb06719.x
Subject(s) - german , biology , research center , rna processing , cancer , library science , genetics , rna , gene , medicine , pathology , computer science , philosophy , linguistics
We have characterized a transcription factor from Ehrlich ascites cells that is required for ribosomal gene transcription by RNA polymerase I (Pol I). This factor, termed TIF‐IC, has a native molecular mass of 65 kDa, associates with Pol I, and is required both for the assembly of Sarkosyl‐resistant initiation complexes and for the formation of the first internucleotide bonds. In addition to its function in transcription initiation, TIF‐IC also plays a role in elongation of nascent RNA chains. At suboptimal levels of TIF‐IC, transcripts with heterogeneous 3′ ends are formed which are chased into full‐length transcripts by the addition of more TIF‐IC. Moreover, on a tailed template, which allows initiation in the absence of auxiliary factors, TIF‐IC was found to stimulate the overall rate of transcription elongation and suppress pausing of Pol I. Thus TIF‐IC appears to serve a function similar to the Pol II‐specific factor TFIIF which is required for Pol II transcription initiation and elongation.