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The Golgi apparatus (/ ˈ ɡ ɒ l dʒ i /), also known as the Golgi complex, Golgi body, or simply the Golgi, is an organelle found in most eukaryotic cells. [1] Part of the endomembrane system in the cytoplasm, it packages proteins into membrane-bound vesicles inside the cell before the vesicles are sent to their destination.
The Golgi apparatus, which participates in glycosylation and transport of proteins and lipids in the secretory pathway, consists of a series of stacked cisternae (flattened membrane sacs). Interactions between the Golgi and microtubules are thought to be important for the reorganization of the Golgi after it fragments during mitosis.
The Golgi apparatus is used by the cell for further protein modification. The section of the Golgi apparatus that receives the vesicles from the ER is known as the cis face, and is usually near the ER. The opposite end of the Golgi apparatus is called the trans face, this is where the modified compounds leave.
The Golgi apparatus plays a pivotal role in N-linked glycosylation, a process that begins in the ER and is elaborated within the Golgi. Through the sequential trimming and addition of sugars like GlcNAc, mannose, galactose, and sialic acid, the Golgi ensures that proteins are properly modified for their final functional roles.
These are then returned to the cytoplasm as new cell-building materials. To accomplish this, lysosomes use some 40 different types of hydrolytic enzymes, all of which are manufactured in the endoplasmic reticulum, modified in the Golgi apparatus and function in an acidic environment. [15]
Other compartments such as peroxisomes, lysosomes, the endoplasmic reticulum, the cell nucleus or the Golgi apparatus are not of endosymbiotic origin. Smaller elements like vesicles , and sometimes even microtubules can also be counted as compartments.
Glycosylation of the proteoglycan occurs in the Golgi apparatus in multiple enzymatic steps. First, a special link tetrasaccharide is attached to a serine side chain on the core protein to serve as a primer for polysaccharide growth. Then sugars are added one at a time by glycosyl transferase.
The Golgi apparatus, which participates in glycosylation and transport of proteins and lipids in the secretory pathway, consists of a series of stacked cisternae (flattened membrane sacs). Interactions between the Golgi and microtubules are thought to be important for the reorganization of the Golgi after it fragments during mitosis. [ 6 ]