Patrick Brennwald

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Epithelial differentiation involves the generation of luminal surfaces and of a noncentrosomal microtubule (MT) network aligned along the polarity axis. Columnar epithelia (e.g., kidney, intestine, and Madin-Darby canine kidney [MDCK] cells) generate apical lumina and orient MT vertically, whereas liver epithelial cells (hepatocytes and WIFB9 cells)(More)
We have identified a pair of related yeast proteins, Sro7p and Sro77p, based on their ability to bind to the plasma membrane SNARE (SNARE) protein, Sec9p. These proteins show significant similarity to the Drosophila tumor suppressor, lethal giant larvae and to the neuronal syntaxin-binding protein, tomosyn. SRO7 and SRO77 have redundant functions as loss of(More)
Many genes required for cell polarity development in budding yeast have been identified and arranged into a functional hierarchy. Core elements of the hierarchy are widely conserved, underlying cell polarity development in diverse eukaryotes. To enumerate more fully the protein-protein interactions that mediate cell polarity development, and to uncover(More)
The Rho family GTPase Cdc42 is a key regulator of cell polarity and cytoskeletal organization in eukaryotic cells. In yeast, the role of Cdc42 in polarization of cell growth includes polarization of the actin cytoskeleton, which delivers secretory vesicles to growth sites at the plasma membrane. We now describe a novel temperature-sensitive mutant, cdc42-6,(More)
The Rho3 and Cdc42 members of the Rho GTPase family are important regulators of exocytosis in yeast. However, the precise mechanism by which they regulate this process is controversial. Here, we present evidence that the Exo70 component of the exocyst complex is a direct effector of both Rho3 and Cdc42. We identify gain-of-function mutants in EXO70 that(More)
Temporal and spatial regulation of membrane-trafficking events is crucial to both membrane identity and overall cell polarity. Small GTPases of the Rab, Ral and Rho protein families have been implicated as important regulators of vesicle docking and fusion events. This review focuses on how these GTPases interact with the exocyst complex, which is a(More)
Rho GTPases are important regulators of polarity in eukaryotic cells. In yeast they are involved in regulating the docking and fusion of secretory vesicles with the cell surface. Our analysis of a Rho3 mutant that is unable to interact with the Exo70 subunit of the exocyst reveals a normal polarization of the exocyst complex as well as other polarity(More)
At steady state, most Rho GTPases are bound in the cytosol to Rho guanine nucleotide dissociation inhibitors (RhoGDIs). RhoGDIs have generally been considered to hold Rho proteins passively in an inactive state within the cytoplasm. Here we describe an evolutionarily conserved mechanism by which RhoGDI1 controls the homeostasis of Rho proteins in eukaryotic(More)
Rab guanosine triphosphatases regulate intracellular membrane traffic by binding specific effector proteins. The yeast Rab Sec4p plays multiple roles in the polarized transport of post-Golgi vesicles to, and their subsequent fusion with, the plasma membrane, suggesting the involvement of several effectors. Yet, only one Sec4p effector has been documented to(More)
Kin1 and Kin2 are Saccharomyces cerevisiae counterparts of Par-1, the Caenorhabditis elegans kinase essential for the establishment of polarity in the one cell embryo. Here, we present evidence for a novel link between Kin1, Kin2, and the secretory machinery of the budding yeast. We isolated KIN1 and KIN2 as suppressors of a mutant form of Rho3, a(More)