Concept explainers
RIPs as Cancer Drugs Researchers are taking a page from the structure-function relationship of RIPs in their quest for cancer treatments. The most toxic RIPs, remember, have one domain that interferes with ribosomes, and another that carries them into cells. Melissa Cheung and her colleagues incorporated a peptide that binds to skin cancer cells into the enzymatic part of an RIP, the E. coli Shiga-like toxin. The researchers created a new RIP that specifically kills skin cancer cells, which are notoriously resistant to established therapies. Some of their results are shown in FIGURE 9.17.
FIGURE 9.17 Effect of an engineered RIP on cancer cells. The model on the left shows the enzyme portion of E. coli Shiga-like toxin engineered to carry a small sequence of amino acids (in blue) that targets skin cancer cells. (Red indicates the active site.) The graph on the right shows the effect of this engineered RIP on human cancer cells of the skin (); breast () liver (); and prostate ().
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Biology: The Unity and Diversity of Life (MindTap Course List)
- In the: Inhibition of splicing by ribozymes Explain: (a) What is the process affected? (b) What is the Effect on the process? (c) Does it affect prokaryotes, eukaryotes or both?arrow_forwardThe steroid progesterone has an important role in the female reproductive system. Researchers interested in studying membrane progestin receptors (MPRS) developed a method to produce and purify the protein in active form. First, the researchers devised a way to prepare a specific MPR known as hMPRA using the machinery of yeast cells. In order to facilitate purification and identification in later studies, they manipulated the yeast cells so that they attached two different tags to the C-terminal end of the protein. The first tag, Compound 1, is a peptide sequence that acts as an epitope, part of a much larger peptide sequence that is recognized by the immune system. The second sequence consisted of six consecutive histidine residues (His). This sequence binds tightly to Ni2+ cations. In chromatography, (His), tag labeled proteins can be eluted from Ni²+. supported columns by adding a small molecule to the eluent that mimics the side chain of histidine.…arrow_forwardThe steroid progesterone has an important role in the female reproductive system. Researchers interested in studying membrane progestin receptors (MPRs) developed a method to produce and purify the protein in active form. First, the researchers devised a way to prepare a specific MPR known as hMPRA using the machinery of yeast cells. In order to facilitate purification and identification in later studies, they manipulated the yeast cells so that they attached two different tags to the C-terminal end of the protein. The first tag, Compound 1, is a peptide sequence that acts as an epitope, part of a much larger peptide sequence that is recognized by the immune system. The second sequence consisted of six consecutive histidine residues (His). This sequence binds tightly to Ni2+ cations. In chromatography, (His), tag labeled proteins can be eluted from Ni²+- supported columns by adding a small molecule to the eluent that mimics the side chain of histidine. After preparing hMPRA, the…arrow_forward
- eading list Cells have oligosaccharides displayed on their cell surface that are important for cell-cell recognition. Your friend has discovered a transmembrane glycoprotein, GP1, on a pathogenic fungal cell that is recognized by human immune cells. He decides to purify large amounts of GP1 by expressing it in bacteria. To his purified protein he then adds a branched 14-sugar oligosaccharide to the asparagine of the only Asn-X- Ser sequence found on GP1. Unfortunately, immune cells do not seem to recognize this synthesized glycoprotein. What's a likely explanation for this problem? O The oligosaccharide needs to be further modified before it's mature. O The oligosaccharide should've been added one sugar at a time. O The oligosaccharide needs a disulfide bond. O The oligosaccharideehould've been added to the serine instead of the asparagine.arrow_forwardMany blood clotting proteins undergo a post-translational modification in which specific glutamic acid residues (Glu) in the protein are converted to gamma-carboxyglutamic acid residues (Gla). See reaction scheme below. An example is the blood clotting protein Factor IX, which has 12 Glu in its N-terminus converted to Gla. This modification gives Factor IX the ability to bind calcium and phospholipid membranes. Bacteria do not have the enzyme required to convert Glu to Gla and therefore Factor IX proteins expressed in bacteria would not have the proper modifications. How might you engineer the translational apparatus of a bacterial cell line so that it produces Factor IX with Gla in the appropriate positions. How would you ensure that only the 12 Glu in Factor IX that are normally converted to Gla and not just all Glu (Limit 5-6 senetnces)?arrow_forwardI need an example to study for an testarrow_forward
- Please help with this as soon as you can, thank you.arrow_forwardOnce the chains of peptides that make up lysyl-tRNA synthetase protein are synthesized in ribosomes, lysyl-tRNA synthetase needs to have the proper active site in order to perform its function, explain the process of protein folding necessary to have a proper 3-D structure, include effect of thermodynamics and different states in folding, including what happen when there are prolines that form peptide bonds with other amino acids, and any disulfide bridgesarrow_forwardWhat enzyme catalyzes protein synthesis in bacteria? You discover a new broad-spectrum antibiotic that inhibits protein synthesis and named it Compound J. You want to determine the mechanism of action of Compound J. After treating bacteria cells with Compound J, you observe many ribosomes with long polypeptide chains bound to them. Based on this observation, make a hypothesis about which part of the ribosome Compound J is binding and how this specifically affects translation. What evidence supports that proper protein folding is essential to all domains of life? Name and describe the function/s of two specific molecules that help proteins fold in bacteria.arrow_forward
- The previously accepted model of the chloramphenicol action was that it inhibited all ribosomes equally. Why were the authors of the Marks, 2016 paper skeptical of this model? Choose all that are correct. Because they had observed that certain bacteria were resistant to chloramphenicol, and this proves that chloramphenicol stalls ribosomes at certain sites within those bacteria. Because certain MRNA templates had been observed to be inhibited by chloramphenicol more strongly than others Because chloramphenicol induces expression of chloramphenicol resistance proteins through translational arrest at specific codons in the leader ORFS of chloramphenicol resistance genes, which suggests there is preferential stalling at certain sites. Because chloramphenicol induces expression of chloramphenicol resistance proteins - therefore, these proteins must be able to be translated during chloramphenicol treatment. Because chloramphenicol binds the decoding center of the 30S subunit, and there are…arrow_forwardProteins called molecular chaperones assist in the process of protein folding. One class of chaperones found in organisms from bacteria to mammals is heat shock protein 90 (Hsp90). All Hsp90 chaperones contain a 10 amino acid signature sequence that readily allows identification of these proteins in sequence databases. Two representations of the Hsp90 signature sequence are shown here. Y-x-[NQHD]-[KHR]-[DE]-[IVA]-F-[LM]-R-[ED]. 4 YSNKE/FLRE 3. 7. 1 1 2 3 4 5 6 7 8 9 10 C Bitsarrow_forwardIn the: Mutation of the 28S RNA preventing the binding of the 40S with 60S ribosomes Explain: (a) What is the process affected? (b) What is the Effect on the process? (c) Does it affect prokaryotes, eukaryotes or both?arrow_forward
- Biology: The Unity and Diversity of Life (MindTap...BiologyISBN:9781305073951Author:Cecie Starr, Ralph Taggart, Christine Evers, Lisa StarrPublisher:Cengage Learning