ons in the FSHR protein can increase cancer risk. FSHR is characterized e. Norma
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Question
ons in the FSHR protein can increase cancer risk. FSHR is characterized e. Normal function of this receptor involves binding to it's ligand orn 2 (1pt). Mutati s a proto-oncogene. functi the outside of the cell. Ligand binding results in changes in conformation of the cytoplasmic domain of the receptor that results in activation of a G-protein protein. One common mutation in FSHR occurs at amino acid 436, where W is replaced with C (W436C). This mutation occurs in a domain of the protein that likely binds to the ligand that activates the receptor. Let's practice protein analysis using this mutation. I will lead you through the logic below. First, think about the difference in chemistry between W and C. Are they similar or different? Write your answer below.(0.25pts) a. b. Next, are there any special properties associated with w and C other than being polar, nonpolar, acidic, or basic? Write your answer below. (0.25pts) At this point you should realize that there is a definite difference in chemistry between W (normal amino acid) and C (mutation). How might that affect tertiary structure?? (0.25pts) c. d. Lastly, changes in structure affect function. If the normal protein (FSHR) is activated by binding to its ligand (FSH). What would happen with a mutation that causes it to become an oncogene...overactive (gain of function) or nonfunctional (loss of function)? (0.25pts)Explanation / Answer
a. W is Tryptophan amino acid and C stands for Cysteine. Tryptophan has aromatic rings in int and it is non-polar in nature where as cysteine is polar in nature has functional group sulphur. Hence both are different chemically.
b. Tryptophan absorb UV-light at 280 nm because of its aromatic ring where as cysteine is responsible for disulphide linkage in protein which is one of the major driving force for proper folding of protein.
c. As mentioned cysteine is involved in disulphide linkage in a protein, replacing tryptophan with cysteine causes improper disulphide linkage and hence affects tertiary structure of the protein and also its function.
d. Mutation which leads to conversion of proto-oncogene to oncogene is a gain of function type of mutation. The function which is normally not present in cell is gained due to mutation. Hence cell becomes overactive.
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