Concepts in Bioscience Engineering by Richard Dods

Author:Richard Dods
Language: eng
Format: epub
ISBN: 9783030283032
Publisher: Springer International Publishing

In the rough ER, the macromolecules (the cargo: lipids and glycoproteins) are sequestered in a vesicle acquired from the pinching off from the ER membrane. The vesicle with its cargo enters the cis side of the Golgi apparatus. The vesicle fuses with the Golgi membrane. The cargo enters the lumen and is modified by enzymes. Another vesicle forms and carries the cargo to the next sac, fuses with the membrane of the Golgi apparatus, is modified by another enzyme(s), and is encased in another vesicle.

The procedure continues for up to 100 times before the cargo emerges from the cell by exocytosis. Some vesicles remain intact and carry their cargo to the lysosomes and other cell types. The last sac finishes, organizes, and packages the cargo adding the “address” where this cargo is to reside (lysosomes, enzymes, mucus, hormones, etc.). The modifications that occur during the cargo transport through the Golgi apparatus are additions and deletions of sugars and additions of metal ions.

The lysosomal vesicle originates from a budding off from the Golgi membrane. The lysosome carries hydrolytic enzymes that were originally made in the ER and modified in the Golgi apparatus. Lysosomes coalesce with vesicles that contain materials that will be hydrolyzed to their component molecules (glucose, fatty acids, amino acids, etc.). Thus, the lysosomes are scavengers taking large macromolecules and hydrolyzing them to their components. They function as cellular recycling centers.

How do the vesicles move with their cargos through the Golgi apparatus? A Cold Spring Harbor article presents five of the principal theories. First the authors build the observations, 13 of them, that must be explained in the hypothesis. Then they grade five possible solutions or models according to their strengths and weaknesses. Tentative conclusions are made. This article was authored in 2011. Read this article and decide for yourself which of the five models adheres to the most plausible explanation. Glick BS, Luini A. (2011).Models for Golgi traffic: A critical assessment. ColdSpringHarbPerspectBiol:3:a005215. doi:10.1101/cshperpect.a005215.

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