PCF4 encodes an RNA polymerase III transcription factor with homology to TFIIB.
A dominant mutation in the PCF4 gene of S. cerevisiae was isolated as a suppressor of a tRNA gene A block promoter mutation. In vitro studies indicate that PCF4 is a stoichiometrically-required RNA polymerase III (pol III) transcription initiation factor. We show that the PCF4-1 mutation increases the number of transcriptionally competent preinitiation complexes by affecting a limiting activity in yeast cell extracts that is squelched by excess TFIIIC. The PCF4 gene encodes a TFIIB homolog whose size, biochemical, and genetic properties are consistent with those of the 70 kd subunit of TFIIIB. The TFIIB homology of PCF4 suggests a means for determining the polymerase specificity of a gene.
López-De-León
A
A
Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461.
Librizzi
M
M
Puglia
K
K
Willis
I M
IM
D000595:Amino Acid Sequence; D006801:Humans; D008969:Molecular Sequence Data; D012320:RNA Polymerase III / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D035581:Transcription Factor TFIIB; D014157:Transcription Factors / Q000235:genetics*; D014158:Transcription, Genetic
D035581:Transcription Factor TFIIB; D014157:Transcription Factors; D012320:RNA Polymerase III