Plasmodesmata Are Membrane Lined Cytoplasmic Channels

Bordered Pits Plants

PD are specialized intercellular channels that establish both cytoplasmic and endomembrane continuity in plants (Robards and Lucas 1990 Lucas and Wolf 1993 Roberts and Oparka 2003). Unlike animal cells, plant protoplasts are encased by rigid cell walls, preventing the PMs of neighboring cells from making direct contact. This physical limitation imposed upon plant cells may have driven the creation of membrane-lined cytoplasmic pores as means of a symplasmic communication, which is essential to...

Types of Trafficking at the Plasma Membrane

Protein trafficking at the plasma membrane (PM) involves (1) secretion of proteins to the PM or to the apoplast (exocytosis, secretion, or anterograde trafficking), (2) uptake of proteins at the PM for recycling or regulation of their activity (endocyto-sis or retrograde trafficking), and (3) moving proteins from one location on the PM to another (transcytosis). The integration of these processes is required for dynamic Department of Horticulture and Landscape Architecture, Purdue University,...

Aquaporins

For a long time, biological textbook knowledge stated that water is able to diffuse freely through biomembranes. Biophysical studies have shown something different water fluxes into and out of cells cannot be explained by simple diffusion. The surprising discovery of water-transporting membrane proteins aquaporins (AQP) changed the view at water transport trough membranes and the regulation of water relations in plants (Agre 2004). The sequenced plant genomes of Arabidopsis and rice contain 35...

The Pinformed Pin Transporter Family

The family of PIN transporters represents plant-specific membrane proteins - most of them localized to the PM - that use auxin as their transport substrate. This attributes an important function to this family of transport proteins as the activity of PIN proteins generates auxin gradients and flux maxima. They are essential for regulating processes such as morphogenesis, flowering, embryo development, organ patterning, and primordia development as well as a diverse suite of environmental...