Anaphase initiation in Saccharomyces cerevisiae is controlled by the APC-dependent degradation of the anaphase inhibitor Pds1p.

Anaphase initiation has been postulated to be controlled through the ubiquitin-dependent proteolysis of an unknown inhibitor. This process involves the anaphase promoting complex (APC), a specific ubiquitin ligase that has been shown to be involved in mitotic cyclin degradation. Previous studies demonstrated that in Saccharomyces cerevisiae, Pds1 protein is an anaphase inhibitor and suggested that it may be an APC target. Here we show that in yeast cells and in mitotic Xenopus extracts Pds1p is degraded in an APC-dependent manner. In addition, Pds1p is directly ubiquitinated by the Xenopus APC. In budding yeast Pds1p is degraded at the time of anaphase initiation and nondegradable derivatives of Pds1p inhibit the onset of anaphase. We conclude that Pds1p is an anaphase inhibitor whose APC-dependent degradation is required for the initiation of anaphase.