Figure 1

Rat brain cDNA expression library screening in yeast identifies a plasmid containing an approximately 1.4 kb cDNA fragment capable of enhancing RXR transcriptional activation. (A) Yeast cells transformed with the β-galactosidase reporter vector YRpβRE and the yeast expression vector YEpRXRα were exposed to increasing concentrations of 9-cis retinoic acid (9cRA). The βGal activity present in yeast extracts was measured as the colorimetric change of the βGal substrate ONPG (A₄₁₅) normalized for cell number approximations (A₆₀₀). The dose response of YRpβRE transformed yeast is also shown (Reporter Alone). Values reported are averages of duplicate data points. (B) An outline of the screening strategy used to identify a RXR transcriptional enhancing cDNA product. Transformed yeast expressing rat brain cDNA products that elevate transcription of the βGal reporter gene result in the formation of blue colonies. (C) BJ5409 yeast cells were transformed with the transcription reporter plasmid YRpβRE(2), co-transformed with either YEpRXRα or pcRB1.4 expression plasmids and YRpβRE(2), or co-transformed with YEpRXRα, pcRB1.4 and YRpβRE(2). The βGal activity present in yeast extracts was measured as in (A). Values reported are averages of multiple data points and error bars reflect standard deviations, n = 3.