Phosphorylation of a Protein by a Protein Kinase …

Question

Phosphorylation of a protein by a protein kinase …
A) adds two positive charges to the protein.
B) activates the protein.
C) deactivates the protein.
D) can create a binding site for other proteins.
E) requires the hydrolysis of two molecules of ATP per phosphorylated residue.

Accepted Answer

Phosphorylation of a protein (typically coupled to one ATP hydrolysis per reaction) adds negative charges to the protein, potentially changing its surface chemistry and recruiting binding partners that recognize the phosphorylated protein. Some proteins are activated by this modification, while some are not, or are even inactivated.