Evidence for an unusual transmembrane configuration of AGG3, a class C Gγ subunit of Arabidopsis.

Heterotrimeric G proteins are crucial for the perception of external signals and subsequent signal transduction in animal and plant cells. In both model systems, the complex comprises one Gα, one Gβ, and one Gγ subunit. However, in addition to the canonical Gγ subunits (class A), plants also possess two unusual, plant-specific classes of Gγ subunits (classes B and C) that have not yet been found in animals.

The endoplasmic reticulum is the main membrane source for biogenesis of the lytic vacuole in Arabidopsis.

Vacuoles are multifunctional organelles essential for the sessile lifestyle of plants. Despite their central functions in cell growth, storage, and detoxification, knowledge about mechanisms underlying their biogenesis and associated protein trafficking pathways remains limited. Here, we show that in meristematic cells of the Arabidopsis thaliana root, biogenesis of vacuoles as well as the trafficking of sterols and of two major tonoplast proteins, the vacuolar H(+)-pyrophosphatase and the vacuolar H(+)-adenosinetriphosphatase, occurs independently of endoplasmic reticulum (ER)-Golgi and post-Golgi trafficking.

Routes to the tonoplast: the sorting of tonoplast transporters in Arabidopsis mesophyll protoplasts.

Vacuoles perform a multitude of functions in plant cells, including the storage of amino acids and sugars. Tonoplast-localized transporters catalyze the import and release of these molecules. The mechanisms determining the targeting of these transporters to the tonoplast are largely unknown.

Novel PSI domains in plant and animal H+-inositol symporters.

Inositols are indispensable components of cellular signaling molecules, and impaired cytoplasmic inositol concentrations affect cellular development. Although most cells can synthesize inositol de novo, plasma membrane-localized inositol uptake systems are indispensable for normal development. Here, we present in-depth functional analyses of plasma membrane-localized H(+)-inositol symporters from human and from the higher plant Arabidopsis thaliana.