안녕하세요 ^^ 

ATP -> ADP + P 로 바뀐 것은 phosphorylation 이 아닌 hydrolysis 아닌가요? 

--> 네 hydrolysis 가 맞는 표현입니다. the ATP is hydrolyzed into ADP and Phosphate

그런데 그 Phosphate가 붙은 다른 molecule, 은 phosphate가 붙었으니 phosphorylated되는 겁니다. 

protein 의 특정한 amino acid (PO42-이랑 interact 할수 있는 polar a.a, 혹은 +chargae a.a에) 에  

phosphate (PO42-)이 붙어서 phosphorylated됨으로써,   protein의 모양이 바뀌고, 

function이 바뀌는것을 ( 주로 activate됩니다) protein phosphorylation 이라고 합니다. 아래 글은 

https://raybiotech.com/learning-center/7-ways-to-study-protein-phosphorylation/ 에서 

가져온것이니 한번 읽어보세요 도움이 될겁니다 ^^

Protein phosphorylation is the most well-studied post translational modification (PTM), 

in which a phosphoryl group from adenosine triphosphate (ATP) is 

covalently attached to a serine (~86%), threonine (~12%), or tyrosine (~2%) 

by a kinase and removed by a phosphatase (Figure 1). 

Phosphorylation can modify protein structure, function, and interactions. 

As such, phosphorylation plays a critical role in virtually all cellular processes 

in homeostasis and disease, including signal transduction, cell cycle,