Assembly of scaffold-mediated complexes containing Cdc42p, the exchange factor Cdc24p, and the effector Cla4p required for cell cycle-regulated phosphorylation of Cdc24p.
Enviado por Javier E Irazoqui el
Título | Assembly of scaffold-mediated complexes containing Cdc42p, the exchange factor Cdc24p, and the effector Cla4p required for cell cycle-regulated phosphorylation of Cdc24p. |
Publication Type | Journal Article |
Year of Publication | 2001 |
Autores | Bose, I, Irazoqui, JE, Moskow, JJ, Bardes, ES, Zyla, TR, Lew, DJ |
Journal | J Biol Chem |
Volume | 276 |
Issue | 10 |
Pagination | 7176-86 |
Date Published | 2001 Mar 9 |
ISSN | 0021-9258 |
Palabras clave | Adaptor Proteins, Signal Transducing, Alleles, Binding Sites, cdc42 GTP-Binding Protein, Cell Cycle, Cell Cycle Proteins, Cytoskeleton, Fungal Proteins, Glutathione Transferase, Guanine Nucleotide Exchange Factors, Guanosine Diphosphate, Guanosine Triphosphate, p21-Activated Kinases, Phosphoric Monoester Hydrolases, Phosphorylation, Plasmids, Precipitin Tests, Promoter Regions, Genetic, Protein Binding, Protein Structure, Tertiary, Protein-Serine-Threonine Kinases, Proto-Oncogene Proteins, Recombinant Fusion Proteins, Saccharomyces cerevisiae Proteins, Temperature, Time Factors |
Abstract | In budding yeast cells, the cytoskeletal polarization and depolarization events that shape the bud are triggered at specific times during the cell cycle by the cyclin-dependent kinase Cdc28p. Polarity establishment also requires the small GTPase Cdc42p and its exchange factor, Cdc24p, but the mechanism whereby Cdc28p induces Cdc42p-dependent polarization is unknown. Here we show that Cdc24p becomes phosphorylated in a cell cycle-dependent manner, triggered by Cdc28p. However, the role of Cdc28p is indirect, and the phosphorylation appears to be catalyzed by the p21-activated kinase family member Cla4p and also depends on Cdc42p and the scaffold protein Bem1p. Expression of GTP-Cdc42p, the product of Cdc24p-mediated GDP/GTP exchange, stimulated Cdc24p phosphorylation independent of cell cycle cues, raising the possibility that the phosphorylation is part of a feedback regulatory pathway. Bem1p binds directly to Cdc24p, to Cla4p, and to GTP-bound Cdc42p and can mediate complex formation between these proteins in vitro. We suggest that Bem1p acts to concentrate polarity establishment proteins at a discrete site, facilitating polarization and promoting Cdc24p phosphorylation at specific times during the cell cycle. |
DOI | 10.1074/jbc.M010546200 |
Alternate Journal | J. Biol. Chem. |
PubMed ID | 11113154 |