J. Biol. Chem., Vol. 265, Issue 11, 6131-6138, Apr, 1990
Identification and purification of a yeast transcriptional trans- activator. The yeast homolog of the Rous sarcoma virus internal enhancer binding factor
L Karnitz, D Poon, PA Weil and R Chalkley
Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee 37232.
A cis-acting transcriptional activation sequence (IES2) from the Rous
sarcoma virus internal enhancer was found to stimulate transcription of a
heterologous gene in Saccharomyces cerevisiae. A hamster protein (termed
IBF) which binds to IES2 and stimulates transcription in vitro has
previously been purified and was found to have a subunit molecular mass of
40,000 (Karnitz, L., Poon, D., Weil, P.A., and Chalkley, R. (1989) Mol.
Cell. Biol. 9, 1929-1939). The identification and purification of the yeast
homolog of IBF (yIBF) is reported here. Purified yIBF has a subunit
molecular mass of 92,000. This protein functions as a trans-activator of
transcription in a heterologous HeLa transcription extract in a cis-element
sequence-dependent manner in vitro.