Consider the receptor tyrosine kinase (RTK) from the signaling pathway on the pr
ID: 177852 • Letter: C
Question
Consider the receptor tyrosine kinase (RTK) from the signaling pathway on the previous page. The RTK is a protein that has a single membrane-spanning domain, with a ligand binding domain that resides extracellularly and a cytoplasmically-located kinase domain. When you look at the mRNA that encodes the RTK, you see that when translated, the RTK will have two hydrophobic domains: one at its very N-terminus and one about 1/3rd of the way through the protein from the n-terminus. Explain why there are two hydrophobic domains, even though the RTK has single membrane-spanning domain at the plasma membrane. In your answer, be sure to explain: the function of the N-terminal hydrophobic domain and what happens to this hydrophobic domain. 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 the membrane spanning hydrophobic domain, the ligand-binding domain, and the kinase domain on the drawing. Describe a mechanism that explains why the binding of RingA to API allows API 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.Explanation / Answer
Each RTK monomer has an extracellular N terminal and an intracellular C terminal. The N terminal region has many Growth factors that bind extracellular ligands. The intracellular domain contains catalytic domains that promote kinase activity. Generally these receptors dimerize after binding with ligands to enable further signal transduction processes.
When a growth factor at N terminal binds with its ligand, both of them dimerize and undergo phosphorylation of tyrosine in Cytoplasmic enzyme domain. This reaction further activates tyrosine protein kinase and catalyse the intracellular reactions later on.