Protein vesicular transport within cell

RabGGTase acts specifically on Rab proteins. The Rab proteins are involved in vesicular transport within the cell, with many of the proteins localized in specific compartments of the secretory and endocytic pathways. The Rab family displays a set of one or two cysteine-containing C-terminal motifs (CC, CXC, CCX, CCXX, CCXXX, CXXX) and is (di) geranylgeranylated by RabGGTase. This is achieved in a ternary complex of... 

Orci, L., Glick, B. S. and Rothman, J. E. A new type of coated vesicular carrier that appears not to contain clathrin its possible role in protein transport within the Golgi stack. Cell 46 171-184,1986. 

Figure 1.6 Vesicular transport of proteins within the cell. Vesicles from the endoplasmic reticulum [A] carry protein to the Golgi complex, they are repackaged in the Golgi from which they leave to form primary lysosomes [B] or fuse with the plasma membrane this is to add proteins or to be secreted from the cell [C]. In the Golgi, new vesicles are formed to transport the proteins to the plasma membrane (e.g. transport proteins or proteins for export) or the lysosomes. This system transports, safely, dangerous hydrolytic enzyme to the lysosomes and it also protects membrane proteins, or proteins for export, from degradation in the cytosol.

Phospholipids and cholesterol must be transported from their site of synthesis to various membrane systems within cells. One way of doing this is through vesicular transport, as is the case for many proteins in the secretory pathway. However, most phospholipid and cholesterol membrane-to-membrane transport in cells is not by Golgi-mediated vesicular transport. What is the evidence for this statement What appear to be the major mechanisms for phospholipid and cholesterol transport ... 

Cell-free systems have been largely used to study the vesicular transport of proteins between the endoplasmic reticulum (ER) and the Golgi apparatus (GA) or within the Golgi apparatus [1-2]. 

The sequence of events that result in neurotransmission of information from one nerve cell to another across the s)mapses begins with a wave of depolarization which passes down the axon and results in the opening of the voltage-sensitive calcium charmels in the axonal terminal. These charmels are frequently concentrated in areas which correspond to the active sites of neurotransmitter release. A large (up to 100 M) but brief rise in the calcium concentration within the nerve terminal triggers the movement of the synaptic vesicles, which contain the neurotransmitter, towards the synaptic membrane. By means of specific membrane-bound proteins (such as synaptobrevin from the neuronal membrane and synaptotagrin from the vesicular membrane) the vesicles fuse with the neuronal membrane and release their contents into the synaptic gap by a process of exocytosis. Once released of their contents, the vesicle membrane is reformed and recycled within the neuronal terminal. This process is completed once the vesicles have accumulated more neurotransmitter by means of an energy-dependent transporter on the vesicle membrane (Table 2.3). 

The epithelial membrane of the GI tract consists of a continuous barrier of cells, which allows the transport of low-molecular-weight molecules by simple diffusion or various carrier processes. Macromolecules such as proteins may be absorbed from the intestinal lumen by cellular vesicular processes, through fluid-phase endocytosis (pinocytosis), or by receptor-mediated endocytosis or transcytosis (Fig. 6). In pinocytosis, extracellular fluid is captured within an epithelial membrane vesicle. It begins with the formation of a pocket... 

In both procedures, a gene encoding an abundant membrane glycoprotein (G protein) from vesicular stomatitis virus (VSV) Is Introduced Into cultured mammalian cells either by transfection or simply by Infecting the cells with the virus. The treated cells, even those that are not specialized for secretion, rapidly synthesize the VSV G protein on the ER like normal cellular secretory proteins. Use of a mutant encoding a temperature-sensitive VSV G protein allows researchers to turn subsequent protein transport on and off. At the restrictive temperature of 40 °C, newly made VSV G protein Is misfolded and therefore retained within the ER by quality control mechanisms discussed in Chapter 16, whereas at the permissive temperature of 32 C, the accumulated... 

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