Ypi1, a Positive Regulator of Nuclear Protein Phosphatase Type 1 Activity inSaccharomyces cerevisiae
- 1 March 2008
- journal article
- Published by American Society for Cell Biology (ASCB) in Molecular Biology of the Cell
- Vol. 19 (3), 1032-1045
- https://doi.org/10.1091/mbc.e07-05-0499
Abstract
The catalytic subunit of protein phosphatase type 1 (PP1) has an essential role in mitosis, acting in opposition to the Ipl1/Aurora B protein kinase to ensure proper kinetochore-microtubule interactions. However, the regulatory subunit(s) that completes the PP1 holoenzyme that functions in this capacity is not known. We show here that the budding yeast Ypi1 protein is a nuclear protein that functions with PP1 (Glc7) in this mitotic role. Depletion of cellular Ypi1 induces mitotic arrest due to activation of the spindle checkpoint. Ypi1 depletion is accompanied by a reduction of nuclear PP1 and by loss of nuclear Sds22, a Glc7 binding partner that is found in a ternary complex with Ypi1 and Glc7. Expression of a Ypi1 variant that binds weakly to PP1 also activates the spindle checkpoint and suppresses the temperature sensitivity of an ipl1-2 mutant. These results, together with genetic interactions among YPI1, GLC7, and SDS22 mutants, indicate that Ypi1 and Sds22 are positive regulators of the nuclear Glc7 activity that is required for mitosis.Keywords
This publication has 79 references indexed in Scilit:
- Kinetochore Microtubule Dynamics and Attachment Stability Are Regulated by Hec1Cell, 2006
- The Conserved KMN Network Constitutes the Core Microtubule-Binding Site of the KinetochoreCell, 2006
- Global landscape of protein complexes in the yeast Saccharomyces cerevisiaeNature, 2006
- Regulation of yeast glycogen phosphorylase by the cyclin-dependent protein kinase Pho85pBiochemical and Biophysical Research Communications, 2005
- Optimized cassettes for fluorescent protein tagging in Saccharomyces cerevisiaeYeast, 2004
- Global analysis of protein localization in budding yeastNature, 2003
- Systematic identification of protein complexes in Saccharomyces cerevisiae by mass spectrometryNature, 2002
- Improved method for high efficiency transformation of intact yeast cellsNucleic Acids Research, 1992
- Multifunctional yeast high-copy-number shuttle vectorsGene, 1992
- A protein inhibitor of rabbit liver phosphorylase phosphataseBiochemical and Biophysical Research Communications, 1975