Kinase is an enzyme whose function is to activate another
enzyme from its precursor. This activation is achieved by transferring a phosphate group (phosphorylation) from ATP (adenosine triphosphate), or other high-energy
phosphate, to the precursor molecule. For this reason, kinases are also
known as phosphotransferases.
The role of kinase in muscle action
1. Acetylcholine is released from a motor nerve. This causes an entry
of calcium into the muscle cell. 2. Calcium activates phosphorylase
kinase 3. Phosphorylase kinase phosphorylates phosphorylase, which
is activated 4. Glycogen is broken to glucose. This is used to generate
ATP 5. The muscle works and requires energy in the form of ATP. 6.
The muscle contains muscle cells 7. Contractile proteins in the muscle
are activated by calcium.
The largest group of kinases consists of the protein kinases. An example
is peptidase which is secreted by the small intestine and converts trypsinogen