Identification of Novel Membrane-binding Domains in Multiple Yeast Cdc42 Effectors

• DOI: 10.1091/mbc.e07-07-0676
• Publication Date: 2007-10-04T01:11:02Z
• Authors: Satoe Takahashi; Peter M. Pryciak
• Keywords: CDC42

The Rho-type GTPase Cdc42 is a central regulator of eukaryotic cell polarity and signal transduction. In budding yeast, regulates mitogen-activated protein (MAP) kinase signaling in part through the PAK-family Ste20. Activation Ste20 requires Cdc42/Rac interactive binding (CRIB) domain, which mediates its recruitment to membrane-associated Cdc42. Here, we identify separate domain that interacts directly with membrane phospholipids critical for function. This short region, termed basic-rich (BR) can target green fluorescent plasma vivo binds PIP 2 -containing liposomes vitro. Mutation basic or hydrophobic residues BR abolishes polarized localization function both MAP kinase–dependent independent pathways. Thus, required but insufficient; instead, direct by also required. Nevertheless, phospholipid specificity not essential vivo, because be replaced several heterologous lipid-binding domains varying lipid preferences. We functionally important two other yeast effectors, Gic1 Gic2, suggesting cooperation between protein–protein protein–membrane interactions prevalent mechanism during Cdc42-regulated perhaps dynamic events at cortex.