Non-26S Proteasome Proteolytic Role of Ubiquitin in Plant Endocytosis and Endosomal Trafficking The Structural Changes of the Basal Region of Wheat Proembryo in Relation to Nurture Absorption pH-sensitive Fluorescent Proteins and Their Applications in Plant Cell Biology Plasma Membrane Positioning Mechanism of Auxin Efflux Carrier PIN Proteins Pollen Tube Growth: a Delicate Equilibrium Between Secretory and Endocytic Pathways