The common structure and activities of four subspecies of rat brain protein kinase C family

AbstractElucidation of the complete sequences of four cDNA clones (α, βI, βII, and γ) of the rat brain protein kinase C family has revealed their common structure composed of a single polypeptide chain with four constant (C1-C4) and five variable (V1-V5) regions. Although these sequences are highly homologous and closely related to one another V3-, V4-, and V5-regions of γ-subspecies are slightly bigger than the corresponding regions of the other three subspecies. The first constant region, C1, contains a tandem repeat of cysteine-rich sequence (6, total 12 cysteine residues). The third constant region, C3, has an ATP-binding sequence which is found in many protein kinases. In adult rat whole brain, the relative activities of α-, βI, βII, and γ-subspecies are roughly 16, 8, 55, and 21%, respectively. γ-Subspecies is expressed after birth apparently only in the central nervous tissue, implying its role in the regulation of specific neuronal functions