A Novel FKS06- and Rapamycin-binding Protein (FPR3 Gene Product) in the Yeast Saccharomyces cerevisiae Is a Proline Rotamase Localized to the Nucleolus
Abstract. The gene (FPR3) encoding a novel type of peptidylprolyl-cis-trans-isomerase (PPIase) was isolated during a search for previously unidentified nuclear proteins in Saccharomyces cerevisiae. PPIases are thought to act in conjunction with protein chaperones because they accelerate the rate of conformational interconversions around proline residues in polypeptides. The FPR3 gene product (Fpr3) is 413 amino acids long. The 111 COOH-terminal residues of Fpr3 share greater than 40 % amino acid identity with a particular class of PPIases, termed FK506-binding proteins (FKBPs) because they are the intracellular receptors for two immunosuppressive compounds, rapamycin and FK506. When expressed in and purified from Escherichia coli, both full-length Fpr3 and it
