Myristoyl coenzyme A (myristoyl-CoA) is a derivative of CoA that contains the long-chain fatty acid myristic acid . It is a substrate for N-myristoyltransferase during myristoylation, a process that adds a myristoyl group to proteins either during translation to modify protein activity or post-translationally in apoptotic cells. It is also a substrate in the de novo synthesis of phosphatidylinositol .