Ribosom RE

7/27/2019 Ribosom RE

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RIBOSOME & RETICULUM

ENDOPLASMIC

By: Kamel


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RIBOSOM


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Processing of pre rRNA


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Ribosome Assembly


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Prokariotik


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Eukariotik


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ENDOMEMBRANESYSTEM


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THE SECRETORY PATHWAY


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Overview of Protein Sorting


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Contranslational


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Posttranslational


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Nucleus: Nuclear localization signal


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Mitochondria


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Peroxisome


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Types of Integral Membrane


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Type I


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Type II

both

Signal-anchor sequence that

functions as both an ER signal

sequence and membrane-

anchor sequence.


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Type III

The signal-anchor sequence, which is located

near the N-terminus, inserts the nascent chain

into the ER membrane with its N-terminus

facing the lumen


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Type IV


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P i M difi i F ldi d


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Protein Modifications, Folding, and

Quality Control in The RE

1. Glycosylation

2. Formation of disulfide bonds in the ER

3. Proper folding of polypeptide chains andassembly of multisubunit proteins in the ER


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Glycosylation

The addition of carbohydrate side chain to

specific amino acid residues of protein

N- linked glycosylation: oligosaccharida-

asparagin

O- linked glycosylation: serine/ threonine


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three glucose (Glc),

nine mannose (Man),

two Nacetylglucosamine

(GlcNAc) molecules, which

can be written as

Glc3Man9(GlcNAc)2


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f d lf d b d h


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Formation of disulfide bonds in the ER

disulfide bonds (

S

S

) help stabilize the tertiary

and quaternary structure of many proteins.

In eukaryotic cells, disulfide bonds are formed only in

the lumen of the rough ER Thus disulfide bonds are found only in secretory

proteins

The efficient formation of disulfide bonds in the

lumen of the ER depends on the enzymeprotein

disulfide isomerase (PDI), which is present in all

eukaryotic cells.


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Proteolytic Processing


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Control in RE


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mooth RE


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mooth RE

&

LipidSynthesis


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Colesterol


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Carbohydrate Metabolism

Glykogen Glucose

Glucose 6 phosphate glucose

Enzym: glycogen phosphorylase


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The cytochrome P450 enzyme system detoxifies many foreign

compounds the body encounters. However, P450 activity can

also make some compounds more toxic or mutagenic (for

example, some cigarette smoke compounds). To function, the

P450 enzymes require electrons to be provided by anotherprotein, typically CPR. We are investigating the genetics and

developmental biology of CPR using the Drosophila model

system. CPR is encoded by a single gene in both humans and

flies. The figure depicts the extremely pleiotropic nature ofCPR, which supplies electrons to scores of P450 isoforms. Each

P450 may in turn process many different substrates.
http://drnelson.utmem.edu/CytochromeP450.htmlhttp://www.blackwell-synergy.com/doi/abs/10.1111/j.1349-7006.2004.tb03162.xhttp://www.blackwell-synergy.com/doi/abs/10.1111/j.1349-7006.2004.tb03162.xhttp://www.uky.edu/Pharmacy/ps/porter/CPR.htmhttp://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=124015http://flybase.bio.indiana.edu/reports/FBgn0015623.htmlhttp://en.wikipedia.org/wiki/Pleiotropyhttp://en.wikipedia.org/wiki/Pleiotropyhttp://flybase.bio.indiana.edu/reports/FBgn0015623.htmlhttp://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=124015http://www.uky.edu/Pharmacy/ps/porter/CPR.htmhttp://www.blackwell-synergy.com/doi/abs/10.1111/j.1349-7006.2004.tb03162.xhttp://www.blackwell-synergy.com/doi/abs/10.1111/j.1349-7006.2004.tb03162.xhttp://drnelson.utmem.edu/CytochromeP450.html


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Ribosom RE