The Golgi Complex

Structure and Function of Golgi Complex

• Animal cells typically contain 10 to 20 Golgi complexes, each consisting of flattened, membrane-enclosed, disc-shaped compartments called cisternae.
• The Golgi complex comprises three membrane-enclosed components: cisternae, small vesicles, and larger vacuoles.
• The endoplasmic reticulum (ER) sends proteins and lipids to the Golgi apparatus for modification and processing.
• The Golgi complex has two distinct poles: the cis-face (entry face) and the trans-face (exit face), connected to special regions called cis and trans Golgi networks.
• The Golgi complex functions as a factory for processing, segregating, and distributing proteins to various cellular destinations.
• It has five functional regions: cis-Golgi network, cis-Golgi, medial-Golgi, trans-Golgi, and trans-Golgi network, each containing different enzymes for protein modification.
• The primary function of the Golgi apparatus is the processing of proteins targeted to the plasma membrane, lysosomes, secretory granules, and sorting and packaging them into specific transport vesicles.
• The Golgi complex is compartmentalized, and proteins are modified step by step, with enzymes catalyzing early processing steps near the cis face and later processing steps toward the trans face.
• The modification of proteins in the Golgi complex involves glycosylation, proteolytic processing, glycolipid and sphingomyelin biosynthesis, and sorting of proteins.
• Glycosylation of proteins in the Golgi involves modification and synthesis of carbohydrate portions of glycoproteins, resulting in complex oligosaccharides and high-mannose oligosaccharides.
• Specific modifications occur in specific subcompartments of the Golgi, with specific sugar molecules added or deleted to modify the branched sugar structures found on newly formed proteins.
• N-linked oligosaccharides in the Golgi prevent the misfolding of proteins and their aggregation, and they undergo specific modifications at different stages within the Golgi complex.

Structure and Function of the Golgi Complex

• Animal cells typically contain 10 to 20 Golgi complex per cell, each consisting of flattened, membrane-enclosed, disc-shaped compartments called cisternae.
• The Golgi complex has three membrane-enclosed components: cisternae, small vesicles, and larger vacuoles.
• The endoplasmic reticulum (ER) sends proteins and lipids to the Golgi apparatus, which receives and modifies them.
• The Golgi complex has two distinct poles: the cis-face (entry face) and the trans-face (exit face).
• The Golgi complex functions as a factory for processing, segregating, and distributing proteins to the plasma membrane, secretory vesicles, and lysosomes.
• The cis and trans faces are connected to special regions called cis Golgi network (CGN) and trans Golgi network (TGN).
• The Golgi complex has five functional regions: cis-Golgi network, cis-Golgi, medial-Golgi, trans-Golgi, and trans-Golgi network, each containing different enzymes which modify the proteins.
• The primary function of the Golgi apparatus is processing proteins targeted to the plasma membrane, lysosomes, secretory granules, and sorting and packaging them into specific transport vesicles.
• The Golgi complex is compartmentalized, with proteins being modified step by step, and enzymes catalyzing early and later processing steps located in different regions.
• Proteins are modified in the Golgi complex through glycosylation, involving the addition and removal of specific sugar residues.
• Two types of N-linked oligosaccharides are attached to mammalian glycoproteins: complex oligosaccharides and high-mannose oligosaccharides, with specific modifications occurring in specific subcompartments.
• Glycosylation in the Golgi serves the purpose of preventing the misfolding and aggregation of proteins.