Cellular morphogenesis, including polarized outgrowth, promotes tissue shape and function. Polarized vesicle trafficking has emerged as a fundamental mechanism by which protein and membrane can be targeted to discrete subcellular domains to promote localized protrusions. Frizzled (Fz)/planar cell polarity (PCP) signaling orchestrates cytoskeletal polarization and drives morphogenetic changes in...

The RAB5 GTPase ARA6 of Arabidopsis thaliana is known to be involved in endosomal trafficking by targeting vesicles to the plasma membrane. During this process AtARA6 is working in close relationship with the SNARE protein VAMP727 (vesicle associated membrane protein 727). Recently, ARA6 of the characean green algae Chara australis (CaARA6) was shown to have properties similar to AtARA6, pointi...

Identifying the proteins that regulate vesicle trafficking is a fundamental problem in cell biology. In this paper, we introduce a new assay that involves the expression of an FKBP12-rapamycin-binding domain-tagged candidate vesicle-binding protein, which can be inducibly linked to dynein or kinesin. Vesicles can be labeled by any convenient method. If the candidate protein binds the labeled ve...

Mechanisms governing dynamic protein recycling include small GTPases that activate/inactivate their partner proteins to affect cytoskeletal dynamics, and thereby polar growth, asymmetric cell shape and physiological responses to external stimuli. Three recent studies illustrate the control of PIN endocytosis by ROP-RIC activity in leaf pavement cells and root cells.

Physically separating daughter cells during cytokinesis requires contraction of an actin-myosin ring and vesicle-mediated membrane addition at the cleavage furrow. To identify vesicle trafficking proteins that function in cytokinesis, we screened deficiencies and mutations of candidate genes by live imaging the mitotic domains of the Drosophila embryo. In embryos homozygous for some of these de...

Nitric oxide (NO) is a second messenger with diverse roles in the cardiovascular system, such as inhibiting thrombosis and limiting vascular inflammation. One mechanism by which NO modulates such disparate physiological processes is by regulating protein trafficking within cells. NO inhibits exocytosis of endothelial granules which would otherwise trigger inflammation. NO also blocks platelet s...

Here, we present emerging ideas surrounding the interplay between the actin cytoskeleton and receptor transport and activation. The bulk of actin dynamics in cells is thought to contribute to architecture and mobility. Actin also contributes to trafficking, acting as a molecular scaffold, providing force to deform membranes, facilitating vesicle abscission or propelling a vesicle through the cy...

The exocyst complex plays a critical role in targeting and tethering vesicles to specific sites of the plasma membrane. These events are crucial for polarized delivery of membrane components to the cell surface, which is critical for cell motility and division. Though Rho GTPases are involved in regulating actin dynamics and membrane trafficking, their role in exocyst-mediated vesicle targeting...

Due to their well-defined pathways of vesicle trafficking and manyfold mutants ciliates have served as good model systems. Further studies required the development of databases, now available for Paramecium and Tetrahymena. A variety of key players have been identified and characterized based on BLAST search, domain analysis, localization, and gene-silencing studies. They include NSF (N-ethylma...

Hexavalent chromium [Cr(VI)] is a non-essential metal for normal plants and is toxic to plants at high concentrations. However, signaling pathways and molecular mechanisms of its action on cell function and gene expression remain elusive. In this study, we found that Cr(VI) induced endogenous reactive oxygen species (ROS) generation and Ca(2+) accumulation and activated NADPH oxidase and calciu...