Phosphorylation of Amino acids

Phosphorylation is a critical post-translational modification that plays a pivotal role in regulating protein function, signaling pathways, and cellular processes. In this modification, a phosphate group is added to a protein, altering its activity, stability, or localization. Although phosphorylation can occur on several amino acid residues, the most common targets include serine, threonine, and tyrosine. Among the options given, tyrosine is the correct answer because it is one of the primary amino acids targeted by phosphorylation. This modification is catalyzed by enzymes known as kinases, specifically tyrosine kinases in the case of tyrosine phosphorylation, affecting numerous signaling pathways and cellular functions. Problem: In the context of post-translational modifications, which amino acid residue is targeted by phosphorylation? A) Alanine B) Glutamine C) Tyrosine D) Methionine