BIO130H1 Lecture Notes - Lecture 18: Golgi Apparatus, Translocator Protein, Transmembrane Protein

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Path of transmembrane protein from translation to the plasma membrane: cytosol er. Will be targeted to translocator in er membrane: er golgi. What"s going on in the golgi: glycosylation lipids and proteins. Glycosylations on proteins needed to protect proteins in harsh environments. Protect proteins from being degraded in parts of cell that are very acidic (e. g. lysosomes) Move from er into transport vesicle to golgi. What was in lumen now exposed to extracellular environment: golgi plasma membrane. Note: srp and srp receptor still involved in this process. Srp will recognize signal sequence, target nascent polypeptide still being translated by ribosome to membrane, facilitate association of polypeptide with translocator of er membrane. 2 different types of proteins inserted through this process. Sequence of amino acids in protein itself determine how it goes through translocator. Protein a: hydrophobic stretch associates with translocator, opens up pore for nascent polypeptide.

Related Questions

29 Most proteins destined to enter the endoplasmic reticulum _________.

(a) are transported across the membrane after their synthesis is complete.

(b) are synthesized on free ribosomes in the cytosol.

(d) are keep binding to Signal recognition particle (SRP) while they are translated.

30 Which of the following choices reflects the appropriate order of locations through which a protein destined for the plasma membrane travels?

(a) lysosome â endosome â plasma membrane

(b) ER â lysosome â plasma membrane

(d) ER â Golgi â plasma membrane

31 Which of the following statements about vesicle budding from the Golgi is false?

(a) COPII can initiate vesicle budding on Golgi membrane.

(b) Some vesicles budded from Golgi membranes move towards ER.

(d) Clathrin molecules act at the cytosolic surface of the Golgi membrane.

32 Which of the following statements is false?

(a) The signal sequences on mitochondrial proteins are first bound to translocator on outer membrane after translation.

(b) Most mitochondrial proteins are not imported from the cytosol but are synthesized inside the mitochondria.

(c) Chaperone proteins in the mitochondria facilitate the movement of proteins across the outer and inner mitochondrial membranes.

(d) Mitochondrial proteins cross the membrane in their unfolded state.

orangeplatypus673

please help me answer theses questions correctly

1/ Which of the following are required for one-pass transmembrane proteins?

I. N-terminal signal sequence

II. Binding of SRP to the SRP receptor

III. Presence of stop-transfer sequence

IV. Presence of start-transfer sequence

a) I and III

b) I, II, and III

c) II, III, and IV

d) I, II, III, and IV

___________________

2/ Which of the following statements about the signal-recognition particle (SRP) is FALSE?

a) The SRP binds to the ER signaling sequence after the entire protein has been translated by the ribosome.

b) The SRP cycles between the ER membrane and the cytosol.

c) The SRP is required for peptides destined for either the ER membrane or ER lumen.

d) The SRP recognizes the signal sequence at the N-terminus of the newly forming polypeptide.

______________________

3) t-SNARES are _____.

a) found on the cytosolic side of the vesicle membrane.

b) necessary for recognition and transport of proteins into the nucleus.

c) usually located on the target membrane.

d) necessary for vesicle formation.

ceruleanchimpanzee878

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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BIO130H1 Lecture Notes - Lecture 18: Golgi Apparatus, Translocator Protein, Transmembrane Protein

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