Golgi complex and its functions

1. Golgi complex
By Harinatha Reddy
Department of Life sciences
Christ University
Bangalore

2. Introduction:
 Golgi is made up of a series of flattened sacs called cisternae.
 The Golgi complex, functions as a factory in which proteins and
lipids received from the ER are further processed and sorted.
 After processing the protein or lipids transport to their
destinations: lysosomes endosomes and plasma membrane.

3.  The Golgi apparatus was one of the first organelles to be
discovered and observed in detail.
 It was discovered in 1898 by Italian physician Camillo Golgi during
an investigation of the nervous system.

4. convex
concave
Entry face
Exit face

5. STRUCTURE OF GOLGI:
 Golgi complex consisting of two main networks: the cis Golgi
network (CGN) and the trans Golgi network (TGN).
 Proteins from the ER enter at its cis face (entry face), which is
convex and usually oriented toward the nucleus.
 They are then transported through the Golgi and exit from its
concave trans face (exit face).

6. Protein processing within the Golgi:
 Protein processing within the Golgi involves the modification and
synthesis of the carbohydrate portions of glycoproteins.
 One of the major aspects of this processing is the modification of
the N-linked oligosaccharides.
 Plasma membrane proteins is the best example for N-linked
oligosaccharides modification in Golgi apparatus.

7.  The first modification is the removal of three mannose molecules,
this is followed by the sequential addition of an one N-
acetylglucosamine.
 The second modification is removal of two more mannoses, and
the addition of a fucose and two more N-acetylglucoseamines.
 Finally, three galactose and three sialic acid residues are added.

8.  The enzymes that carry out the addition of sugar residues, is the
glycosyltransferases.
 The enzymes that are responsible for the removal of sugars are
glycosidases.

10. Lipid Metabolism in the Golgi:
 The glycerol phospholipids, cholesterol, and ceramide are
synthesized in the SER.
 Sphingomyelin and glycolipids are then synthesized from
ceramide in the Golgi apparatus.
 Sphingomyelin (the only non-glycerol phospholipid in cell
membranes) is synthesized by Golgi.

11. Protein and lipids export from the Golgi Apparatus:
 Proteins as well as lipids and polysaccharides are transported from
the Golgi apparatus to their final destinations through the
secretory pathway.
 This involves the sorting of proteins into different kinds of
transport vesicles, which bud from the trans Golgi network and
deliver their contents to the appropriate cellular locations.

12. THANK YOU