Protein sorting and targeting

The delivery of newly synthesized protein to their proper cellular destination, usually referred to as protein targeting or sorting.
The mode of protein transport depends chiefly on the location in the cell cytoplasm of the polysomes involved in protein synthesis.

There are two modes of protein sorting:-
1) Co - translational Transportation.
2) Post - translational Transportation.

1. By
KAUSHAL KUMAR SAHU
Assistant Professor (Ad Hoc)
Department of Biotechnology
Govt. Digvijay Autonomous P. G. College
Raj-Nandgaon ( C. G. )

2. Contents-
Introduction of protein sorting
Types of protein sorting
Import ants of protein sorting
Conclusion

3. Introduction -
The delivery of
newly synthesized
protein to their
proper cellular
destination, usually
referred to as
protein targeting or
sorting.

4. Modes of protein Sorting -
The mode of protein transport depends chiefly on
the location in the cell cytoplasm of the polysomes
involved in protein synthesis.
There are two modes of protein sorting:-
1) Co -translational Transportation.
2) Post -translational Transportation.

5. Co –Translational Transportation
Protein synthesized on membrane bound polysome
being to enter the endoplasmic reticulum as they are
being synthesized called Co-Translational
transportation of protein.
In this process some organelles are involve given
below-
1)Endoplasmic reticulum
2) Golgi complex
3) Lysosome

6. Endoplasmic reticulum-
Fig-Co translational targeting of secretory proteins to the ER

7. Figure:-Insertionofamembraneproteinwithacleavablesignalsequenceandasinglestop-transfer
sequence

8. Figure:-Insertion of a protein that spans the membrane multiple times

9. Glycosylation of protein in ER-

10. Figure :-Vesicular transport from the ER to the Golgi

11. The Golgi apparatus-
Figure :-Regions of the Golgi apparatus

12. Figure:-Processing ofN-linked oligosaccharides in the Golgi

13. Figure :-Targeting of lysosomal proteins by phosphorylation of mannose residues

14. Figure:-Transport from the Golgi apparatus

15. Post-Translational transportation-
Most proteins are cotranslationally translocated, some are
translated in the cytosol and later transported to their
destination. This occurs for proteins that go to a
mitochondrion, a chloroplast.
This process is called Post-Translational transportation.
1) Mitochondria
2) choloroplast
3) Peroxisomes

16. Mitochondria-
Figure :-Protein import into
the mitochondrial matrix

17. Chloroplast-
Figure :-
Import of rubisco small (S) subunits into the chloroplast
stroma and the assembly of small and large (L)
subunits into the active rubisco enzyme

18. Figure :Two of the four known pathways
for transporting proteins from
the cytosol to the thylakoid lumen

19. Peroxisomes-
Figure :-Synthesis of catalase and its
incorporation into peroxisomes

20. Importance of protein sorting-
•The delivery of the newly synthesized protein to there correct
destination is most important task.
•ER are assists protein in correct folding chaperones and protein
processing enzymes in the ER lumen.
•The important role of the ER is to identify misfolded protein,
mark them, and divert them to a degradation pathway.
•The Golgi apparatus is thus involved in the processing the broad
range of cellular constitute that travel along the secretory
pathway

21. Reference-
The cell ,a molecular approach,M.Cooper
&Geoffrey,2006
The cell and molecular biology,Lohdish,2
nd
edition