Subcellular distribution of α, and β subunit proteins of Ca2+ /calmodulin-dependent protein kinase II expressed in Chinese hamster ovary cells

AbstractWhen two cDNAs respectively encoding the entire coding regions of α and β subunits of Ca2+ /calmodulin-dependent protein kinase II (CaM kinase II) were introduced into Chinese hamster ovary cells, the expressed α and β subunits were differently associated with subcellular structure. Although α subunit was loosely associated with subcellular structure, about 80% of CaM kinase II acitivity of α subunit was found in soluble fraction. More than 50% of the β subunit bound to the membrane, and the remainder was soluble but was loosely associated with subcellular structure. The relative rate of phosphorylation for substrate proteins of the β subunit bound to membrane was significantly different from that of the soluble form