Biology 1002B Lecture Notes - Lecture 5: Signal Recognition Particle, Transmembrane Domain, Transmembrane Protein

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lemonwater-buffalo91

16 Mar 2016

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Recall: given the primary sequence of a protein can"t determine active site. Big spikes in the hydropathy index = likely a transmembrane protein. Diffusion: driven down a concentration gradient or entropy: facilitate this by having a pore. Active transport: pumping, energy dependent, low concentration to high concentration, entropy is going down so you need energy: atp. This domain should be the same in all subsequent abc transporters. Cystic fibrosis: cftr mutation that is an active transporter (abc, huge: 6000 bases that codes for a protein of 1480 amino acids, most common f508 (70% of cases) 1 amino acid messes everything. Consequences of mucous not being moist: gas exchange is impeded, prone to bacterial infections: cilia stuck and immobile no clearance. Why is cf so common: heterozygote form: carriers, enough copies of wild type cftr proteins to pump chloride ions efficiently, 1 in 2500 caucasians have cf (european descent, 1 in 22 canadians carry the cf allele.

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

goldmanatee250

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

Some cells in plant and animals are specialized for the production and release of a particular chemical, often a protein or some other regulatory molecule. These cells generally produce and release their product only when the proper signal is present. Describe the series of events in this cell that would lead from the perception of this signal to the release of the desired product. Begin by providing specific information on: 1) the transduction of the signal across the membrane by the G protein system with subsequent release of the appropriate second messenger(s); 2) the process by which the signal is amplified by the MAP kinase pathway; 3) how the product(s) produced by the MAP kinase cascade reach the nucleus to initiate the transcription of the relevant gene(s).

Assume now that transcription has already occurred, that a mature mRNA has been produced in the nucleus and has migrated to the cytosol, and that this mRNA has been recruited by a ribosome to initiate translation. Since the protein product is secretory, synthesis of the protein will be associated with the rough endoplasmic reticulum. Continue by providing information on 4) how the free ribosome becomes associated with the endoplasmic reticulum to allow for the release of the synthesized protein into the rough ER; 5) the modification or processing of the protein that occurs in the endoplasmic reticulum; 6) the packaging and/or modification of the protein for transport from the ER to the Golgi apparatus; 7) the modification, processing, and packaging of the protein in the Golgi apparatus; and 8) the steps leading to the eventual release of the target protein from the cell via exocytosis.

coffeebear201

Biology 1002B Lecture Notes - Lecture 5: Signal Recognition Particle, Transmembrane Domain, Transmembrane Protein

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