protein kinase

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Any of a group of kinases that phosphorylate the amino acids serine, threonine, and tyrosine in certain proteins, that regulate essential aspects of cell growth and movement, and that can cause cancer and other diseases when dysfunctional.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun biochemistry a kinase which substrate is a protein