Question

Phospho-mimic mutants of proteins can be generated by replacing

• A. serine with aspartic acid
• B. alanine with glutamic acid
• C. serine with alanine
• D. threonine with glutamic acid

Hint:

Phospho-mimic mutations typically use negatively charged amino acids like aspartic acid or glutamic acid to mimic phosphorylation and affect protein function.

Answer 1

The Correct Option is A, D

Step 1: Understanding phospho-mimic mutations.
Phospho-mimic mutations are substitutions that mimic the effect of phosphorylation. The most common phospho-mimic substitutions are replacing serine, threonine, or tyrosine with negatively charged amino acids like aspartic acid or glutamic acid. This substitution mimics the negative charge introduced by phosphorylation.

Step 2: Analyzing the options.
(A) serine with aspartic acid: This is correct. Aspartic acid is negatively charged, and substituting serine with aspartic acid mimics the negative charge of a phosphorylated serine.
(B) alanine with glutamic acid: This is incorrect. Glutamic acid is also negatively charged, but alanine does not represent a phosphorylatable amino acid.
(C) serine with alanine: This is incorrect. Alanine is neutral and would not mimic the effect of phosphorylation.
(D) threonine with glutamic acid: This is incorrect. While glutamic acid is negatively charged, threonine can be phosphorylated, and replacing it with glutamic acid does not mimic phosphorylation.

Step 3: Conclusion.
The correct answer is (A) serine with aspartic acid, as aspartic acid substitution best mimics the effects of phosphorylation.