This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
Phosphorylation of which amino acid does not occur by protein kinase - 
Select and explain. 
A. Aspargine, B. Threonine, C. Serine, D. Tyrosine
A: Aspargine
Answer: A: Aspargine 
Explanation: Ans. is 'a' i.e., Aspargine Protein kinase mostly add phosphoryl group to a serine, threonine, or tyrosine residues. Some protein kinase target the side chains of histidine, lysine, arginine, aspaic acid and glutamic acid.