The Golgi Apparatus

Presented by: Rahul Kumar

M.Sc 1st Sem.

Life Science

CUG/2014/1073

Contents

History

Organization of Golgi

Functions of the Golgi

.Protein modification

.Synthesis of Sphingomyelin &Glycolipid

.Sorting of protein to lysosome

.Sorting of protein to plasma membrane

Vesicles

History

Discovered by Italian physician Camillo Golgi during an investigation of the nervous system in 1898 – internal reticular structure.

Optical illusion created by the observation technique used by Golgi.

This structure was confirmed in 1910 as a Golgi apparatus/ Golgi bodies.

Organization of Golgi

• Found within the cytoplasm of both plant and

animal cells.

• It is composed of stacks of membrane-bound

structures - cisternae (singular: cisterna)

• Each cisterna comprises a flat, membrane-

enclosed disc that includes special Golgi

enzymes which modify or help to modify

cargo proteins that travel through it.

• Consists of 4 functionally distinct region- cis

face (entry face), medial cisterna, trans cisterna,

trans face(exit face).

• Each region contain different enzymes which

selectively modify the contents depending on

where they reside.

Functions of the Golgi:

E.R Golgi Secretion P.M

Endosome

Lysosome

Modification

Of protein Synthesis

Glycolipid &

Sphingomyelin

Protein modification

• Start in the E.R after translation - addition of 2

N-acetylglucosamine & 9 mannose.

• In Golgi, glycosyltransferase & glycosidase is

present – help in addition & removal of sugar

residues in N-linked oligosaccharides.

Processing of N-linked oligosaccharides in the

Golgi :

Synthesis of Sphingomyelin & Glycolipid

Sorting of protein to lysosome:

Sorting of protein to plasma memsbrane:

• Take place via 3 routes

direct transport from trans golgi .

via an intermediate of endosome .

regulated secretory pathway .

direct transport from trans golgi-

- In corporation of new protein(peripheral as

well as integral) & lipid to the p.m .

- continuous secretion of protein from the cell.

- linear targeting signals.

via an intermediate of endosome

• in the epithelial

cells by transcytosis

• ex.- transport of

antibodies to

extracelluar fluid.

regulated secretory pathway

• Play an important role in

- release of neurotransmiter

-release of hormones

- release of digestive enzymes

Vesicles

• Important role in transport of mole. Between

different membrane or compartment of cell.

• Formation of vesicles require –

-GTP binding protein (ex. Arf, Rab)

-Adaptor protein

-Coat protein (copl, copll, clatrin)

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