Nbp1 is a novel component of the Saccharomyces cerevisiae spindle pole body and a target of the Cdc14 phosphatase.

摘要

The Cdc14 phosphatase of the budding yeast, Saccharomyces cerevisiae , has important roles in regulating the progression of cells through anaphase and telophase including an essential function in terminating mitosis by promoting the suppression of the cyclin-dependent kinase that initiates this phase of the cell cycle. Current studies revealed that Cdc14 not only drives Cdk inactivation but also targets a wide range of substrates involved in orchestrating multiple processes that occur during anaphase and telophase including regulating the stability of the spindle. In a screen for Cdc14 substrates and interacting proteins, our laboratory identified the protein Nbp1 as a potential substrate of Cdc14. Nbp1 is poorly characterized. Our studies demonstrated that Nbp1 is a novel member of the spindle pole body. We generated nbp1 temperature sensitive strains. Characterization of nbp1ts revealed that Nbp1 is required for maintaining normal DNA ploidy and assembly of mitotic spindle. Nbp1 is a phosphoprotein and undergoes a cell cycle dependent phosphorylation. N-terminal Nbp1 is essential; whereas the consensus Cdk phosphorylation sites that change Nbp1 mobility and also affect its association with Clb2 locate to its C-terminus. Our data suggested that Nbp1 is an in vivo substrate of Cdc28-Clb and Cdc14; however, we cannot link the essential function of Nbp1 to its phosphorylation.