Question

You are doing experiments on a protein that is activated by reversible phosphorylation. You are given 2 different versions of this protein.

Version 1 Amino-acid sequence: Methionine-Histidine-Tryptophan-Serine-Glycine
Version 2 Amino-acid sequence: Methionine-Histidine-Tryptophan-Leucine-Glycine

Your results show that Version 2 cannot become activated by reversible phosphorylation. Explain this result in 1 - 3 sentences).

Answer 1

Version 2 of the protein cannot be activated by reversible phosphorylation because it contains leucine instead of serine, an amino acid that cannot be phosphorylated.

Step-by-step explanation:

The inability of Version 2 of the protein to become activated by reversible phosphorylation is due to the substitution of serine with leucine. Serine residue is one of the only three amino acid residues (serine, threonine, tyrosine) that can be phosphorylated, which is crucial for enzyme activation in many signaling and regulatory processes. Leucine cannot be phosphorylated, so the alteration in the amino acid sequence prevents Version 2 of the protein from becoming activated.