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The RNA binding protein La influences both the accuracy and the efficiency of RNA polymerase III transcription in vitro.
Author(s) -
Gottlieb E.,
Steitz J. A.
Publication year - 1989
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.1460-2075.1989.tb03445.x
Subject(s) - transcription (linguistics) , rna polymerase ii , rna polymerase , biology , t7 rna polymerase , rna , microbiology and biotechnology , biochemistry , gene expression , gene , philosophy , promoter , linguistics , escherichia coli , bacteriophage
The autoantigen La binds the U‐rich 3′ ends of all nascent RNA polymerase III transcripts. Here, we demonstrate that this abundant nuclear phosphoprotein not only binds these RNAs but appears to be required for their synthesis. HeLa cell extracts immunochemically depleted of La by either patient or mouse monoclonal antibodies lose greater than 99% of their transcription activity on class III genes. The few transcripts synthesized in the absence of La have fewer uridylate residues at their 3′ ends than those made in its presence. Reconstitution of La‐depleted extracts with biochemically purified HeLa La protein stimulates transcription levels and completely restores transcript length. A model coupling transcription levels to the action of La at the RNA polymerase III termination signal is presented.