13) The following proteins are to be synthesized at the ER and will ultimately be secreted or transmembrane proteins. The start (rectangles) and stop (circles) sequences are indicated. Draw how each will be assembled within the ER. NH2 COOH Cyto ER Lumen NH2 COOH Cyto ER Lumen NH2 COOH Cyto ER Lumen NH2 COOH Cyto ER Lumen 4
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Proteins are synthesized at the ER and will either be secreted or become transmembrane proteins. The diagram shows the cytoplasm (Cyto) and the ER Lumen, separated by a membrane (represented by the curved line). Start sequences initiate translocation into the ER Show more…
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Four membrane proteins are represented in the schematic below. The boxes represent membranespanning domains, the arrows represent sites of cleavage of signal sequences, and the negative and positive signs indicate positive and negatively charged amino acids surrounding those domains. Predict how each of the mature proteins will be arranged across the membrane of the ER. Indicate clearly the N and C terminus relative to the cytosol and ER lumen, and label each transmembrane domain. An example is provided. You can sketch these by hand or you can sketch them electronically using computer drawing tools, and insert a picture of your schematics into your answer file.
Madhur L.
10. The figure shows the organization of a protein that resides on the ER membrane. The N- and C-termini of the protein are labeled. Boxes 1, 2, and 3 represent membrane-spanning sequences. Non-membrane-spanning regions of the protein are labeled “X,” “Y,” and “Z.” Which region(s) of the protein is/are located in the cytoplasm? Which region(s) of the protein is/are located in the lumen of the ER? Which region of theprotein is a stop transfer sequence? Which region of the protein is a start transfer sequence?
Sri K.
Predict the membrane orientation in the endoplasmic reticulum (ER) of a protein that is synthesized with an internal ER anchor sequence (not cleaved off), followed by a stop-transfer sequence and then a start transfer sequence in more C terminal regions of the protein (with no more stop transfer sequences in the most C terminal region). Going from the N terminus to the C terminus, the orientation would be: N terminal end in the lumen, transmembrane segment, C terminal end in the cytosol. N terminal end in the cytosol, transmembrane segment, loop in the lumen, transmembrane segment, loop in the cytosol, transmembrane segment, C terminal end in the lumen. N terminal end in the lumen, transmembrane segment, loop in the cytosol, transmembrane segment, C terminal end in the lumen N terminal end in the cytosol, transmembrane segment, C terminal end in the lumen. N terminal end in the cytosol, transmembrane segment, loop in the lumen, transmembrane segment, loop in the cytosol, transmembrane segment, loop in the lumen.
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