Question
Hello! Please explain, thanks.
Also - 7 out of my last 10 posted questions were answered incorrectly... PLEASE make sure you're positive of your answer <3
2. You discover a signal transduction pathway that regulates actin polymerization. SigC is the ligand, which binds to and activates a receptor tyrosine kinase (RTK). Activation of the RTK leads to the activation of the Ras protein, which then activates the protein kinase PK1 that phosphorylates the RingA protein on S34. When SigC plasma membrane phosphorylated, RingA binds to the gene regulatory SPACE EXTRACELLULAR inactive Ras protein activated Ras protein protein, AP1. When RingA is bound to AP1, AP1 can enter CYTOSOL GDP the nucleus and bind to DNA. to activate transcription of the GTP ARP2/ ARP3 complex, activated RTK op leading to increased actin PK1 polymerization in the cell. A adaptor protein Ras-GEF portion of this signal transduction pathway is RingA diagrammed in the Figure iv) The RTK will travel to the plasma membrane within a vesicle. Draw the orientation of the RTK on a Golgi- derived vesicle (using the picture to the right), and note a) the membrane spanning hydrophobic domain, b) the ligand- binding domain, and c) the kinase domain on the drawing (5 points) inside of vesicle v) Describe a mechanism that explains why the binding of RingA to AP1 allows AP1 to enter the nucleus. The mechanism you propose must be consistent with what you have learned about nuclear transport. Please be as specific as possible with your answer. (5 points)
Explanation / Answer
iv) During secetory pathway, when the vesicle with the cargo protein fuses with the plasma membrane, the inside faced region of the protein becomes the extracellular region of the membrane exposed protein now.
v) The binding of Ring A to AP1 allows AP1 to enter the nucleus because it causes the nuclear import more feasible by making available the site for binding of importin protein to AP1 due to conformational changes in AP1. The importin protein mediates the transportation of AP1 protein complexed with Ring A to enter the nucleus.
