Ca2+/ calmodulin-dependent protein kinase 4 (CAMKⅣ) belongs to the serine/threonine protein kinase family, and to the Ca2+/calmodulin-dependent protein kinase subfamily which is widely recognized as an essential enzyme implicated in the phophoinositide amplification cascade. Ca2+/calmodulin dependent protein kinase (CAMK) can be activated by the introcellular increased Ca2+and then apt to combine with the target protein. Ca2+/ calmodulin-dependent protein kinase 4 (CAMKⅣ) is a multifunctional CaM-dependent kinase protein with limited tissue distribution, that has been implicated in transcriptional regulation in lymphocytes, neurons and male germ cells. All of the isforms of this family, including myosin light chain kinase, phosphorylase kinase, CaMK1, CaMKⅢ and CaMKⅣ have EF-hand structure.

> 95 % as determined by SDS-PAGE