TheSaccharomyces cerevisiae GAM2/SIN3 protein plays a role in both activation and repression of transcription

Abstract
We have cloned GAM2, which is required for transcription ofSTA1, a gene encoding an extracellular glucoamylase inSaccharomyces cerevisiae var.diastaticus. DNA sequence analysis revealed thatGAM2 is the same gene asSIN3, known to be a general negative regulator of yeast genes. RNA blot analysis indicated thatGAM2/SIN3 also acts as a positive regulator ofGAM3/ADR6, which in turn is required for transcription ofSTA1 andADH2. These results suggest thatGAM2 regulatesSTA1 expression through transcriptional activation ofGAM3 and indicate that GAM2/SIN3 protein is a transcriptional regulator that can play a role in both activation and repression of transcription.