Why is histidine phosphorylation more common in prokaryotic organisms than in human cells?

• A. Histidine phosphorylation is a key regulatory mechanism in prokaryotes but is rare in human cells due to different signaling pathways.
• B. Prokaryotes lack other amino acids for phosphorylation.
• C. Human cells do not use phosphorylation for regulation.
• D. Histidine is not present in human proteins.

Answer: (A)