e (x) if the following statements about synthesis of proteins containing an ER sequence are True or False: False i. Translation is initiated by ribosomes located on the ER membrane ii. The signal recognition particle (SRP) binds a sequence of nonpolar (hydrophobic) amino acids. iii. The ER signal sequence may be cleaved by signal peptidase on the cytoplasmic side of the ER membrane. iv. The part of a transmembrane protein that will ultimately be located outside of the cell is inserted into the lumen of the ER during translation. A stop transfer sequence is a series of polar amino acids that halts translocation of a newly synthesized peptide into the ER lumen.

e (x) if the following statements about synthesis of proteins containing an ER sequence are True or False: False i. Translation is initiated by ribosomes located on the ER membrane ii. The signal recognition particle (SRP) binds a sequence of nonpolar (hydrophobic) amino acids. iii. The ER signal sequence may be cleaved by signal peptidase on the cytoplasmic side of the ER membrane. iv. The part of a transmembrane protein that will ultimately be located outside of the cell is inserted into the lumen of the ER during translation. A stop transfer sequence is a series of polar amino acids that halts translocation of a newly synthesized peptide into the ER lumen.

Human Heredity: Principles and Issues (MindTap Course List)

11th Edition

ISBN:9781305251052

Author:Michael Cummings

Publisher:Michael Cummings

Chapter9: Gene Expression And Gene Regulation

Section: Chapter Questions

Problem 18QP: The following is a portion of a protein: met-trp-tyr-arg-gly-pro-thr-Various mutant forms of this...

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Much of procollagen formation occurs in the endoplasmic reticulum and Golgi apparatus which requires signal peptide. All of the following statements about targeting a protein for the ER are true except A. signal peptide usually has a positively charged N-terminus and a stretch of hydrophobic amino acids. B. signal peptide emerging from a free ribosome binds signal recognition particle (SRP). C. signal peptide is usually cleaved from the protein before the protein is inserted into the ER membrane. D. docking protein is actually an SRP receptor and serves to bind the SRP to the ER. E. SRP and docking protein do not enter the ER lumen but are recycled.
gene normally contains an N' terminal ER signal sequence and an internal stop transfer sequence. The ER signal sequence is recognized and used during the protein trafficking process, as normal. After translation is completed a signal peptidase enzyme cleaves the N' ER signal sequence but the internal sequence is not cleaved. Which of the following figures best represents the orientation of the protein product after translation? N Extracellular Extracellular Extracellular Extracellular -N' C' N Lumen Lumen Lumen Lumen N' A В C
Place the steps below in the correct order to accurately reflect the steps by which a secretory protein is co-translationally imported into the lumen of the endoplasmic reticulum: As the polypeptide elongates and translocates into the ER, the signal peptidase cleaves the signal peptide. The SRP binds the SRP receptor, directing the ribosome to dock on the ER membrane. Termination of translation, results in the release of the polypeptide into the ER lumen, release of the ribosome from the ER membrane, and closing of the channel. The signal recognition particle (SRP) binds to the signal sequence on a newly synthesized polypeptide and stalls translation. The channel in the ER membrane opens and the polypeptide is inserted into the ER lumen. The SRP is released. A.6-4-2-3-1-5 B.4-2-5-1-3-6 C.3-1-6-2-4-5 D.1-2-3-4-5-6 E.2-6-1-5-4-3
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Select the best explanation of the unfolded protein response (UPR): O A. The UPR senses misfolded proteins through detection of proteins tagged with polyubiquitin chains and sends them for degradation in the lysosome B. The UPR senses misfolded proteins through recognition of specific oligosaccharide conformations and sends them for degradation via the proteasome C. The UPR senses high levels of misfolded proteins in the ER and activates ubiquitin ligases to add ubiquitin to the misfolded proteins and target them for secretion from the cell. D. The UPR senses ER stress in the form of high levels of misfolded proteins and signals the cell to halt translation and induces expression of ER chaperones
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If the pinsulin receptor, a, example of an integral membrane protein, is cotranslationally inserted into the ER membrane with the N-terminus on the cytosolic side of the membrane and the C-terminus in the lumen of the ER, which side of the receptor would you expect to bind to the ligand, pinsulin, when the it is found on the cell surface? OlA. C-terminal end of the protein will bind pinsulin B. N-terminal end of the protein will bind pinsulin C. Neither will bind to a ligand because both ends of the protein will be cytoplasmic D. Neither will bind to a ligand because both ends of the protein will be extracellular and will compete with each other
The following is a portion of a protein: met-trp-tyr-arg-gly-pro-thr-Various mutant forms of this protein have been recovered. Using the normal and mutant sequences, determine the DNA and mRNA sequences that code for this portion of the protein, and explain each of the mutations. a. met-trp- b. met-cys-ile-val-val-leu-gln- c. met-trp-tyr-arg-ser-pro-thr- d. met-trp-tyr-arg-gly-ala-val-ile-ser-pro-thr-