Conserved and plant-unique mechanisms regulating plant post-Golgi traffic

Abstract

Membrane traffic plays crucial roles in diverse aspects of cellular and organelle functions in eukaryotic cells. Molecular machineries regulating each step of membrane traffic including the formation, tethering, and fusion of membrane carriers are largely conserved among various organisms, which suggests that the framework of membrane traffic is commonly shared among eukaryotic lineages. However, in addition to the common components, each organism has also acquired lineage-specific regulatory molecules that may be associated with the lineage-specific diversification of membrane trafficking events. In plants, comparative genomic analyses also indicate that some key machineries of membrane traffic are significantly and specifically diversified. In this review, we summarize recent progress regarding plant-unique regulatory mechanisms for membrane traffic, with a special focus on vesicle formation and fusion components in the post-Golgi trafficking pathway.

Keywords: Rab GTPase; SNARE; coat protein complex; dynamin-related protein; membrane trafficking; tether.

Figure 1

Model for a general mechanism of membrane trafficking. Coat protein complexes (CPCs) and dynamin-related GTPases (DRPs) participate in the formation of vesicular or tubular carriers. CPCs facilitate cargo selection and membrane deformation, and DRPs take part in the tubulation and/or scission of donor membranes. Rab GTPase promotes the tethering of membrane carriers to the target membrane through effector molecules (Tethers), which is followed by SNARE-mediated membrane fusion.

Figure 2

A schematic illustration of clathrin-coated vesicle formation in land plants. Light blue represents the cytosol; orange, and red lines represent the donor membrane and the clathrin coat, respectively; and green and blue dots represent DRP1 and DRP2 proteins, respectively.