Secretory proteins enter the ER after or concomitant with their synthesis on cytoplasmic ribosomes in a process known as translocation. In either case, nascent secretory proteins must be targeted to the translocation machinery at the ER membrane and must traverse the lipid bilayer of the ER...

Cell polarity refers to the asymmetry in cell shape resulting from asymmetrical proteinrndistribution within a cell in order to serve a specialized cell function or directional cellrndivision. Mechanisms of cell polarization are conserved through evolution and arernachieved by conserved...

Dense core granules (DCGs) are vesicular organelles derived from outbound traffic through the eukaryotic secretory pathway. As DCGs are formed, the secretory pathway can also give rise to other types of vesicles, such as those bound for endosomes, lysosomes, and the cell surface. DCGs differ from...

Fusion of biological membranes plays an important role in cell structure and function. It is essential for organelle biogenesis, vesicle targeting, constitutive and regulated exocytosis, endocytosis, pathogen invasion of host cells, sperm-egg fusion and skeletal muscle formation. This chapter...

In eukaryotic cells, specific mechanisms allow selective packaging of proteins and lipids into transport vesicles, which can then specifically recognize the membrane of the acceptor compartment and fuse with it to deliver their cargo. Formation, transport and docking of vesicles are based on a...

Binding of growth factors and other cell-activating agents to cell surface receptors is known to trigger a complex series of events that initiate signal transduction. Ligand activation of many signal-transducing receptors accelerates receptor endocytosis. The classical view is that receptor...

As the interface between the intracellular and extracellular environments, the plasma membrane forms a barrier to the uptake of nutrients and other macromolecules as well as a defense against pathogens. Specialized endocytic mechanisms direct the internalization of plasma membrane components,...

The movement of proteins between compartments of the secretory and endocytic \r\npathways occurs via vesicles and/or larger carriers. The efficacy of both pathways relies on high fidelity with which the vesicles are delivered to the appropriate target membrane. The initial recognition between a...

Secretion of proteins from eukaryotic cells requires the coordinated function of multiple organelles and cellular machineries. After synthesis and translocation into the endoplasmic reticulum, proteins are exported to the Golgi apparatus, a multi-compartment organelle that is the protein...

Transport of lipid and protein within the early secretory pathway is mediated by small transport vesicles that act as molecular taxis, shuttling cargoes between the endoplasmic reticulum (ER) and Golgi apparatus and within the Golgi. These vesicles are sculpted from donor organelles by distinct...

Eukaryotic cells use multiple pathways for the endocytic entry of proteins and lipids at the plasma membrane. To date, the best characterized pathway is clathrin-mediated endocytosis. This chapter presents an overview of the mechanisms of clathrin-mediated endocytosis and how it is regulated. We...

Membrane traffic pathways require the transport of material between successive organelles, which in neurons may be more than one meter apart. This traffic involves \r\na varied mix of microtubule- and actin-based motility, driven by dynein, kinesin family members and myosins. In this chapter, we...

Membrane proteins are sorted throughout the secretory and endocytic pathway by cis-acting sorting motifs that are recognized in trans by a host of protein machinery. While sorting information for some proteins can be an intrinsic nonregulated property embedded within their primary sequence,...

Trafficking pathways of eukaryotic cells exhibit sophisticated interplay between protein and lipid components. The protein molecules and their interacting networks are fairly well characterised. However, the lipid components and their regulation are much less understood. In this review, we...

For the greater part of the last century, research in the field of protein transport was synonymous with microscopy. Before the end of the century, this view was dramatically changed by the emergence of innovative genetic, molecular and biochemical approaches that revolutionized and invigorated...

The development of a multicellular organism is mostly controlled at the transcriptional level but it has also been shown to require the transport of membrane and proteins through the exocytic pathway to the plasma membrane and the extracellular medium. As they are transported in the different...

Regulated secretion is a defining feature of neurons and endocrine cells. It produces the precisely timed release of chemical messengers that is crucial for the coordination of the complex systems that regulate thought, behavior and body homeostasis. The molecular reactions that underlie...

The secretory and endocytic pathways in eukaryotic cells serve as major routes for protein transport out of and into the cell. Proteins enter the secretory pathway by translocation into the endoplasmic reticulum. Subsequent protein transport between organelles of the secretory pathway is mediated...

During the last two decades, efforts in the protein trafficking field have focused primarily on the identification of the machinery components of vesicular transport and mechanisms that underlie it. In addition, research has started to reveal how intra-cellular trafficking is regulated. Here, we...

All eukaryotic cells contain membrane-bounded compartments that interact with the cell\'s environment. Vesicles transport proteins and lipids between these compartments via two major pathways: the outwards, exocytic pathway, carries material synthesized in the cytoplasm to the cell milieu, and...