Final answer:
In phosphorylation, a phosphate group is linked to a protein through phosphoester bonds, impacting the protein's activity.
Step-by-step explanation:
When a protein is phosphorylated by a kinase, the phosphate is linked to the protein through phosphoester bonds. This process often involves the transfer of the gamma (third) phosphate of ATP to the hydroxyl groups of the amino acids serine, threonine, or tyrosine in the protein structure. The addition of the phosphate group via the kinase's catalytic action results in a conformational change of the protein, which can activate or deactivate its function.
The phosphate group is added by a kinase, and it often results in a shape change in the protein that can activate or turn off its function.