Which of the following is an amino acid side chains can receives a terminal phosphate from an ATP molecule? Serine Threonine Tyrosine None of the above All of the aboveA. SerineB. ThreonineC. TyrosineD. None of the aboveE. All of the above Solution Answer: E. All of the above Explanation: While phosphorylation is a prevalent post-translational modification (PTM) for regulating protein function, it only occurs at the side chains of three amino acids, serine, threonine and tyrosine, in eukaryotic cells. These amino acids have a nucleophilic (–OH) group that attacks the terminal phosphate group (-PO32-) on the universal phosphoryl donor adenosine triphosphate (ATP), resulting in the transfer of the phosphate group to the amino acid side chain..