Page 238 - Color Atlas of Biochemistry

Endoplasmic reticulum and Golgi apparatus 229

A. Protein sorting

Cytoplasmic pathway Secretory pathway
Ribosomes
4 2 -KDEL
+ + +
Protein * H N Rough ER
3
* 1

Retention Cytoplasm

5 *
-SKL H N Retention
2
Golgi complex
7

6
Receptor
R R
8

Peroxisomes Mitochondria 3 Secretory
R * vesicle
Lysosomes 2 +
Nucleus Ca
9
Cell membrane

* Standard pathway (without signal)

B. Translocation signals C. Exocytosis
+ + α-Helix Transmitter Vesicle Rab · GTP
Signal peptide + H N
1 2
(secretory pathway)
+ OOC
Synapto- GTP
brevin
Signal sequence (v-SNARE)
2 Synapto-
(ER proteins) tagmin
...LEDK.... Syntaxin
(t-SNARE)
Mannose 6-
Signal group
3 phosphate 2
(lysosomal proteins) P Synaptic cleft Ca
1. Channel
Apolar
Stop-transfer sequence sequence GTP
4
(membrane proteins)
Synaptotagmin
+ + + releases
Signal peptide v-SNAREs Ca 2 Action
5 (mitochondrial potential
proteins)

...KKKRK... 2. Ca 2
Signal sequence
6
(nuclear proteins) Rab · GDP
GDP
Signal sequence
7 Membrane P
(peroxisomes)
...FKS... fusion SNAP
+NSF
Signal region
8
(secretory vesicle)
3. SNARE complex

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