Essential transcriptional activator that binds the telomeric double-stranded TTAGGG repeat and negatively regulates telomere length. Involved in the regulation of gene expression. Bind both the promoters of ribosomal protein genes and the rDNA locus and activates transcription at these loci. Recruits FHL1 and IFH1 to promoters. Expression is under the control of transcription factors SWI4 and SWI6.