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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.
Golgi apparatus: The primary function of the Golgi apparatus is to process and package the macromolecules such as proteins and lipids that are synthesized by the cell. Lysosomes and peroxisomes: Lysosomes contain digestive enzymes (acid hydrolases). They digest excess or worn-out organelles, food particles, and engulfed viruses or bacteria.
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.
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 ]
In mammals, exocyst components localize in both plasma membrane, and Golgi apparatus and the exocyst proteins are colocalized at the fusion point of the post-Golgi vesicles. The membrane fusion of the constitutive exocytosis, probably, is mediated by SNAP29 and Syntaxin19 at the plasma membrane and YKT6 or VAMP3 at the vesicle membrane.
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 body is also near the rough ER for packaging and redistributing. Likewise, intracellular compartmentalization allows specific sites of related eukaryotic cell functions isolated from other processes and therefore efficient.
Glucose is added onto ceramide from its precursor in the endoplasmic reticulum, before further modifications occur in the Golgi apparatus. [8] Galactose, on the other hand, is added to ceramide already in the Golgi apparatus, where the galactosphingolipid formed is often sulfated by addition of sulfate groups.