Isolation of a Saccharomyces cerevisiae Centromere DNA-Binding Protein, Its Human Homolog, and its Possible Role as a Transcription Factor

A protein that binds specifically to Saccharomyces cerevisiae centromere DNA element I was purified on the basis of a nitrocellulose filter-binding assay. This protein, termed centromere-binding protein 1 (CP1), was heat stable and renaturable from sodium dodecyl sulfate (SDS), and assays of eluates from SDS gels indicated a molecular weight of 57,000 to 64,000. An activity with similar specificity and stability was detected in human lymphocyte extracts, and analysis in SDS gels revealed a molecular weight of 39,000 to 49,000. CP1-binding sites occurred not only at centromeres but also near many transcription units, for example, adjacent to binding sites for the GAL4-positive regulatory protein upstream of the GAL2 gene in S. cerevisiae and adjacent to the TATA element of the adenovirus major late promoter. A factor (termed USF) that binds to the latter site and stimulates transcription has been isolated from HeLa cells by others.