For convenience, the phosphoryl group (PO32-) is represented by .

For convenience, the phosphoryl group (PO32−) is represented by Ⓟ.

This activity is fundamental, because ATP is the main form of energy storage cell: ATP is a carrier of activated phosphoryl group.

Adding or removing a phosphoryl group of proteins is a well-known regulator of many proteins, and it is estimated that human proteins may have as many as 230,000 sites for phosphorylation.

Adding or removing a phosphoryl group to proteins is a well-known regulator for many proteins, and it is estimated that human proteins may have as many as 230,000 sites for phosphorylation.

In addition to coordination with the catalytic magnesium ions, the pKa of the substrate’s alpha hydrogen is also lowered due to protonation of the phosphoryl group by His159 and its proximity to Arg374.

In addition to coordination with the catalytic magnesium ions, the pKa of the substrate's alpha hydrogen is also lowered due to protonation of the phosphoryl group by His159 and its proximity to Arg374.