Golgi Apparatus

1
Golgi Apparatus

• Found in the cells of most eukaryotes (but not
  fungi)
• First identified in 1898 by Italian anatomist
  Camillo Golgi

2
Structure

• Consists of 4-6 cisternae (single membrane sacs)
  which are stacked one on top of the other. The
  edges of the flat sacs are lined with vesicles.

3
The Golgi Post Office

• Can be described as the post office of the
  cell.
• It packages, labels, stores, inspects, and
  perfects proteins synthesized by the Endoplasmic
  Reticulum.
• The Golgi must attach molecular labels to the
  molecules that will be exported, because they
  will need to know where they are going.
• The postal workers, called vesicles, pick up
  packages from the endoplasmic reticulum and take
  them to the edge of the cell membrane after the
  Golgi's work is done.

4
Protein Travel Sequence
5
Parts of the Golgi

• The cis face (closest to the nucleus and the ER)
  - receives transport vesicles from the smooth ER.
  
• The medial Golgi- adds sugars to both lipids and
  proteins.
• The trans Golgi network (closest to the cell
  membrane)- performs proteolysis and sorts
  molecules for their destination.

6
The 3 important roles

• modification of complex molecules (such as
  proteins) by the addition of sugars.
• proteolysis of peptide molecules which makes them
  become active.
• sorting of molecules for either, transport out of
  the cell, incorporation in the cell membrane, or
  transport to another part of the cell.

7
Importance of the GA

• The malfunction of the Golgi Apparatus may be
  associated with the deterioration of long-term
  memory

• The protein mBDNF (mature brain-derived
  neurotrophic factor) is important in the
  formation of long-term memory
• The early form of mBDNF is called pro-mBDNF
• In the GA, pro-mBDNF is supposed to combine with
  CPE (carboxypeptidase E), the enzyme necessary to
  convert pro-mBDNF to mBDNF
• If this binding does not occur, long-term memory
  is affected. Mice that are genetically incapable
  of forming mBDNF demonstrate poor long-term
  memory skills.

8
Importance of the GA

• The malfunction of the Golgi Apparatus may also
  be associated with lysosomal storage disorders

• Lysosomes, produced in the GA, consume/recycle
  foreign objects in order to maintain the natural
  order of the cell
• Lysosomal enzyme deficiencies may prevent
  lysosomes from performing these actions,
  resulting in lysosomal storage disorders