BIOL-4610 Lecture Notes - Lecture 18: Unfolded Protein Response, Galactose, Dolichol

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scarletmouse537

14 Oct 2018

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Cystolic proteins or proteins fed directly into the er. Proteins fed directly into the er have three different pathways they can then take. C. get sent to golgi apparatus for modification. Overview of eukaryotic protein trafficking: secretory pathway (er ribosomes, many proteins are secreted, involved in signaling to other cells, growth factors etc, organellular targeting (free ribosomes, plasma membrane proteins. Bind er signal sequence of newly formed polypeptide. Then it binds to the er membrane. Has alpha and p54 subunit (runs around in cytosol) Binds to hydrophobic portion of signal sequence. Ribosome attaches to mitochondrial membrane: p45 binds to alpha subunit of srp receptor, translocon experiences a conformational change opening to the protein that is beginning to be translated. Gtp is hydrolyzed to gdp giving the translocon energy to change conformations: signal peptidase cleaves the signal sequence, the translocon shuts. Cotranslational import allows some polypeptides to enter er as they are being synthesized.

Related Questions

1. The histones that form the core of the nucleosome get into the nucleus by which of the following?

a) Passive diffusion through nuclear pores

b) Selective and facilitated active transport through nuclear pores

c) Ribosomes located in the nucleus synthetize histones in the nucleus

d) Histones are made at the ER membrane and then diffuse to the nucleus

2. Membrane proteins that belong to the golgi, lysosome, or plasma membrane first pass through which organelle before reaching their final subcellular destination?

a) The golgi apparatus

b) The smooth ER

c) The nucleus

d) The ER membrane

e) The ER lumen

3. Where in the cell would a ribosomal protein be located if it has had its nuclear export signal inactivated (non-functional or non-existent).

a) The protein would be found in the ER lumen

b) The protein would remain in the nucleus

c) The protein would be secreted

d) The protein would remain in the cytoplasm

e) The protein would be in the ER membrane

4. Where would be the final destination of a protein if it contained a NLS anywhere in the protein sequence (and which is exposed to the cytoplasm after protein folding) but also contained an ER signal sequence at the carboxy terminus?

a) The ER lumen

b) The nucleus

c) The cytoplasm

d) The inner nuclear membrane

e) The ER membrane

5. The sequence K-D-E-L serves as a retention/retrieval signal for ER proteins.

a) True

b) False

6. The following are true for both cell membrane proteins and secretory proteins EXCEPT?

a) Precursors of the mature proteins contain signal sequence.

b) Both types of proteins contain stop-transfer sequences

c) Both types of proteins enter the ER while being synthetized

d) Both types of proteins pas through the golgi apparatus

e) Both are carried by clatherin-coated vesicles

7. If you isolate a regulated secreted protein from a secretory/storage vesicle and inject it into the cytosol, is will?

a) Be secreted through channels in the plasma membrane

b) Be taken up into secretory vesicle and secreted

c) Remain in the cytosol until it is degraded

d) Be taken up into the rough ER and follow the secretory pathway

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BIOL-4610 Lecture Notes - Lecture 18: Unfolded Protein Response, Galactose, Dolichol

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