Molecular Cloning of Rat Transcription Factor YY1

YY1 is a ubiquitously expressed multifunctional transcription factor that is involved in both positive and negative regulation of gene expression as well as initiation of transcription. Here, we isolated cDNA encoding a full-length open reading frame (ORF) of rat YY1. Rat YY1 is composed of 411 amino acid residues and its amino acid sequence is 97.6% identical to that of mouse YY1 and 97.8% identical to that of human YY1. The transactivating abilities of wild-type rat YY1 and four truncated mutant forms of YY1 were examined by transient reporter assays. When residues 114-193, which sequence includes a portion of the activation region and most of the Gly/Lys-rich region, were lacking, transactivation activity decreased somewhat, but the further deletion in the activation region (of residues 56-113) did not cause further decrease of the activity. On the other hand, N-terminus of the activation region (1-78/100-106) did not have transactivation activity by itself as well as synergistic activity with an erythroid specific transcription factor GATA-1.