Page 244 - Color Atlas of Biochemistry

Lysosomes 235

A. Structure and contents B. Functions

Approx. 40 different hydrolases Overaged Enzymatic
with acidic pH optima mitochondrion degradation

Secondary
lysosome
Lysosome 1
pH = 4.5 - 5.0
Acid 2
hydrolases
Nucleases
Proteases
Glycosidases 3
Lipases Primary
lysosome
Phosphatases
Sulfatases Residual
body
Phospholipases
Endosome Secondary
lysosome
H
Endocytotic
vesicle
Macro-
Cytoplasm H -transporting molecules,
pH = 7.0 - 7.3 ATPase particles Cell
3.6.1.35
Endocytosis
A H A
P P P PP P or phagocytosis

C. Synthesis and transport of lysosomal proteins

Terminal mannose
1 rER
Protein CH 2 OH
biosynthesis H O
N-Glycosy- H
lation OH HO O R
HO
H H
cis-Golgi Glyco- U
2 apparatus protein P P -GlcNAc
Phosphory- R 1
lation
U
P
CH 2 OH
trans-Golgi
No Man-6- P H O O
3 no transport network H
Binding to OH H O P O
Receptor Man-6- P HO
receptor H NH O
Sorting CH 2
Sealing O C H
Vesicular H O
transport CH 3 OH HO O R
HO
4 H H
7 H O
2
Endo-
lysosome 2
8 Acidification
Dissociation
of the receptor- GlcNAc
protein
5 complex P O CH 2
O
Low pH triggers OHHO
conformational
change Primary HO O
lysosome R
Phosphate 1 GlcNAc-Phosphotransferase 2.7.8.17
6 cleavage
2 GlcNAc-Phosphoglycosidase 3.1.4.45

Koolman, Color Atlas of Biochemistry, 2nd edition © 2005 Thieme
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