Résumé
A novel protein, belonging to the yeast family of FKBPs (FK-binding proteins), FKBP-70, was isolated from
Saccharomyces cerevisiae by its interaction with the immunosuppressive agent FK-520. Its structural gene,
FPR3, was cloned and the protein expressed and purified from
Escherichia coli. This third member of the FKBP family in yeast is homologous to the other FKBPs at its carboxy terminus, showing conserved ligand binding and proline isomerase regions. It is, however,a longer acidic protein with several potential nuclear targeting sequences and a region of homology to nucleolins. Yeast strains deleted for
FPR3, as well as a triple deletion mutant of this family of genes,
FPR1,
FPR2 and
FPR3, are viable under normal conditions of growth, indicating that the
FPR genes are not essential for life.