Endocytosis is a fundamental cellular process by means of which cells internalize extracellular and plasma membrane cargos for recycling or degradation. It is important for the establishment and maintenance of cell polarity, subcellular signaling and uptake of nutrients into specialized cells, but also for plant cell interactions with pathogenic and symbiotic microbes. Endocytosis starts by vesicle formation at the plasma membrane and progresses through early and late endosomal compartments. In these endosomes cargo is sorted and it is either recycled back to the plasma membrane, or degraded in the lytic vacuole. This book presents an overview of our current knowledge of endocytosis in plants with a main focus on the key molecules undergoing and regulating endocytosis. It also provides up to date methodological approaches as well as principles of protein, structural lipid, sugar and microbe internalization in plant cells. The individual chapters describe clathrin-mediated and fluid-phase endocytosis, as well as flotillin-mediated endocytosis and internalization of microbes. The book was written for a broad spectrum of readers including students, teachers and researchers.

Endocytosis is a fundamental biological process, which is conserved among all eukaryotes. It is essential not only for many physiological and signalling processes but also for interactions between eukaryotic cells and pathogens or symbionts. This book covers all aspects of endocytosis in both lower and higher plants, including basic types of endocytosis, endocytic compartments, and molecules involved in endocytic internalization and recycling in diverse plant cell types. It provides a comparison with endocytosis in animals and yeast and discusses future prospects in this new and rapidly evolving plant research field. Readers will find an overview of the state-of-the-art methods and techniques applied in plant endocytosis research.

The transport of macromolecules in membrane bounded vesicles is a fundamental process of all eukaryotic cells. The paths taken by this vesicular traffic have been intensively researched in animal cells but are less well characterised in plant cells. Nevertheless, with the development of and combination of techniques in biochemistry, molecular biology and cell biology, progress in the study of plant vesicle traffic has been achieved in recent years. This book attempts to highlight the recent advances made and to explore avenues for future research. The book opens with a general overview of vesicular traffic both in animal and plant cells. This is followed by a more detailed consideration of higher plant coated vesicles, endocytosis, exocytosis and mechanisms of vesicle traffic and transport in cells. The biochemistry, cell biology and molecular biology of each is considered and particular attention is given to those specialised cell systems in which vesicle traffic is of particular importance. This book brings together expertise from a wide range of research disciplines involved in the study of vesicle traffic in plants, and, as such, provides a unique synthesis from which the research can move forward. It will be of general interest to those involved in the study of vesicle traffic in both plant and animal cells.

In this book, skilled experts provide the most up-to-date, step-by-step laboratory protocols for examining molecular machinery and biological functions of exocytosis and endocytosis in vitro and in vivo. The book is insightful to both newcomers and seasoned professionals. It offers a unique and highly practical guide to versatile laboratory tools developed to study various aspects of intracellular vesicle trafficking in simple model systems and living organisms.

The highly structured eucaryotic cell with its complex division of biochemical labour requires a distinct protein complement in each cellular structure and compartment. Nuclear coded and cytosolically synthesized polypeptides are specifically sorted to every corner of the cell in a post- or co-translational manner. The presence of separate genomes and protein translation machineries in plastids and mitochondria requires further coordination not only on the transcriptional, translational but also most likely on the protein import level. Numerous different protein transport systems have developed and coexist within plant cells to ensure the specific and selective composition of every sub-cellular compartment. This volume summarizes the current knowledge on protein trafficking in plant cells. Aside from the fundamental aspects in cell biology of how specific pre-protein sorting and translocation across biological membranes is achieved, a major focus is on transport, modification and deposition of plant storage proteins. The increasing use of plants as bioreactors to provide custom-designed proteins of different usage requires detailed understanding of these events. This text is directed not only at students and professionals in plant cell and molecular biology but also at those involved in horticulture and plant breeding. It is intended to serve as a text and guide for graduate-level courses on plant cell biology and as a valuable supplement to courses in plant physiology and development. Scientists in other disciplines who wish to learn more about protein translocation in plants will also find this text an up-to-date source of information and reference.

Living cells internalize material from the cell surface using membranous vesicles in a process called endocytosis. The most common mechanism of endocytosis in eukaryotes is clathrin-mediated endocytosis (CME). In CME, many clathrin proteins, in association with numerous other adaptor and accessory proteins, assemble into a cage-like coat that induces the formation of clathrin-coated pits in the plasma membrane. These clathrin-coated pits develop into clathrin-coated membranous vesicles that are released from the plasma membrane into the interior of the cell. The material internalized by CME includes the lipids that comprise the plasma membrane, plasma membrane resident proteins, and other extracellular cargos such as nutrients and hormones. Therefore, CME is crucial to many cellular processes including the maintenance of membrane composition and integrity, the establishment and maintenance of cell polarity, the perception and regulation of cell signaling, and the uptake of nutrients.CME is well characterized in some eukaryotes, such as yeast and mammals, in which many components of the CME machinery have been identified and functionally characterized. Comparatively, the study of CME in plants is in its infancy. The research presented in this dissertation has provided insight into the general CME process in plants, which is similar to CME in other eukaryotes in some regards, but also distinct in many ways. For example, like in yeast and mammals, plants possess a heterotetrameric adaptor protein 2 (AP2) complex, which acts as a core component of CME by interacting with the plasma membrane and recruiting clathrin and specific cargo proteins to the sites of CME. The research presented in Chapters 2 and 3 aided in the original characterization of the AP2 complex in plants. Recent findings show that plants also possess additional CME components that do not exist in yeast or mammals, which could represent the remnants of evolutionarily ancient trafficking machinery. The research presented iniiiChapter 4 explored the function of TWD40-2, a protein that plays a significant role in CME in plants but does not exist in yeast or mammals.Since CME is responsible for the internalization of a large variety of cargo proteins and molecules, CME influences many cellular processes, including the synthesis of the plant cell wall. A majority of the cell wall is comprised of polysaccharides in the form of cellulose, hemicellulose, and pectin. Hemicellulose and pectin are synthesized in the intracellular Golgi apparatus and subsequently delivered to the plasma membrane via vesicular trafficking and discharged into the extracellular cell wall through exocytosis. In contrast, cellulose is synthesized and extruded directly into the cell wall by plasma membrane-resident enzyme complexes, the cellulose synthesis complexes (CSCs). The prerequisite that CSCs must be located at the plasma membrane to function emphasizes the importance of CSC delivery to the plasma membrane and CSC endocytosis from the plasma membrane. In Chapters 2 and 3, the cellulose synthase (CESA) proteins of the CSC were identified as cargos of the CME pathway. In Chapter 4, deficiencies in CME were shown to cause deficiency in the cellulose biosynthesis process by influencing the distribution and behavior of the plasma membrane-localized population of CSCs.Interestingly, without an analogous structure in yeast and mammals, CSCs represent a novel type of CME cargo. Distinct attributes of CSCs, including the localization of CSCs to distinct particles at the plasma membrane, have enabled CSCs to be used as helpful representative cargos of the plant CME pathway. The research presented in this dissertation could be of interest to a broad scientific audience, with implications in the understanding of general processes of the plant cell, such as CME and cellulose biosynthesis, as well as the dissection of specific questions that reside at the crossroads of these two processes.