Golgi vesicles

Figure 6. Transport of material along the nerve axon. Materials such as neurotransmitter peptides are synthesized in the cell body and sequestered in vesicles at the Golgi. Vesicles are then transported down the axon towards the synapse by kinesin motors. Other materials are transported from the synapse to the cell body by dynein motors.

In most plant materials that have been examined, several PME isoforms have been extracted fixDm the cell walls. What is their reqjective fimction How is their synthesis regulated -Immunolocalisation experiments have shown that some Golgi vesicles can be labelled with the JIM 5 antibody, which is known to recognize low-ester pectins [19]. This raises the question of the action pattern of the pectin methyltransferases. Can they produce pectins with different... 

Hasegawa Y, Nakamura S, Kakizoe S, Sato M, Nakamura N. Immunocytochemical and chemical analyses of Golgi vesicles isolated from the germinated pollen of Camellia japonica. J Plant Res 1998 11 421 —429. 

Figure 10 shows small circular vesicles which were distributed at the end of the r-ER cisternae and between the cisternae, and which were sometimes attached to the ER membrane. As the size and the shape of these vesicles (75 nm in mean diameter) were different from those of Golgi-vesicles (130 nm in mean diameter), the small circular vesicles were presumably derived from r-ER they also stained positively with PATAg. These facts suggest that the small circular vesicles from the ER are involved in the biosynthesis and/or transport of non-cellulosic polysaccharides. 

Figure 10. A differentiating tracheid stained with PATAg. Small circular vesicles (arrowheads), distributed near the ER are stained positively. The Golgi-vesicles are also stained positively. Abbreviations are as follows GV, Golgi-vesicle ER, endoplasmic reticulum. Scale bar is 500nm. (Reproduced with permission from Ref. 22. 1986, Japan Wood Research Society.)...

Skjot, M., Pauly, M., Bush, M. S., Borkhardt, B., McCann, M. C., Ulvskov, P. (2002). Direct interference with rhamnogalacturonan I biosynthesis in Golgi vesicles. Plant Physiol, 129, 95-102. 

Figure 5.1 Summary of some transport mechanisms for calcium, phosphate and citrate from the cytosol of the secretory cell to the inside of Golgi vesicles (from Holt, 1981).

On the basis of present evidence, it seems probable that pectic polymers and hemicelluloses are synthesized by the Golgi bodies before transport to the cell wall by Golgi vesicles and insertion intact into the wall after fusion of these vesicles with the plasma membrane.247-249... 

The Golgi membraneous system also occupies a central position in mollusc calcification297. However, different from the coccolithophoridae, the actual CaC03 deposition does not take place inside the Golgi vesicles which are abundant in epithelial cells lining the surface of the outer mantle fold. Instead, the calcification site is an organic matrix released from the extrapallial fluid separating the mantle from the shell. 

The fact that coccolithophoridae deposit their CaC03 inside the Golgi vesicles may be fortuitous. We should remember that calcification is a rather late development in the evolution of brown algae and may be linked to the chemical evolution in the sea. 

Fig. 8. Exocytosis of casein micelles (CM) from Golgi vesicles (G) in the apical region of a bovine mammary gland secretory cell. From Thompson and Farrell (1973), reproduced with permission.

When casein micelles are dissociated, spherical particles are observed with a size similar to the scale of the substructure. Moreover, the number of spherical particles formed by dissociation appears to correspond roughly to the number of substructural elements in the micelle. In electron micrographs of mammary gland secretory cells, some of the Golgi vesicles contain particles of a size similar to that of the particles formed by dissociation of micelles, whereas others contain larger particles. Buchheim and Welsch (1973) proposed that the smaller particles are not small micelles but subunits that are to be assembled into full-sized micelles. The envisaged sequence of assembly is as follows ... 

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