Alanine scanning is a technique to determine the importance

Alanine scanning is a technique to determine the importance of each amino acid to the function of the protein. This technique uses site directed mutagenesis to create a series of mutants, each of which changes a single amino acid to alanine. If the mutant protein maintains comparable function to the original (wild type) protein, this indicates that the mutated amino acid is not essential. However, if the function decreases or is lost, there are several possible effects. For example, certain mutations of the primary structure are so disruptive, the protein is targeted for degradation by the unfolded protein response (UPR). Because the protein is degraded immediately after production, it is not present long enough in the cell to show any function. a. Using what you’ve learned about proteins, describe 3 additional ways that alanine mutation could result in a loss of protein activity. In each case, be sure to explicitely relate how disruption would result in a loss of protein activity. (15 points) b. Most mutations will not result in loss of function, but instead have only a minor decrease in function or no change in function at all. Describe why no loss of function would occur in the context of a hydrophobic amino acid converted to alanine. Also describe why no loss of function would occur in the context of a polar or charged amino acid converted to alanine. (10 points)

Solution

Points: No loss of function hydrophobic:

No loss of function polar: