Molecular cloning and expression of protein kinase C from Bombyx mori

Two partial cDNA clones (Protein kinase C alpha and Protein kinase C iota), each of which encoded a different member of PKC‐protein family, were isolated using RT‐PCR from mRNA of Bombyx mori . The full‐length cDNAs were isolated using SMART‐RACE. The cDNAs were expressed in HepG2 cells and the recombinant proteins were partially purified using an affinity chromatography. Protein kinase C alpha (BPKC alpha) showed a calcium‐dependent kinase activity of histones. Whereas protein kinase C iota (BPKC iota) showed a calcium‐independent activity. Bisindolyl maleimide I, a PKC inhibitor, inhibited these kinase activities. Furthermore, in vitro BPKC alpha interacted and phosphorylated two proteins expressed in the brain of Bombyx mori : Rab protein, which plays important roles in the vesicle transport in the brain, and bMBD2/3, which is a methyl DNA‐binding protein and regulates transcription. These results suggest that these PKCs phosphorylate various substrate proteins and function in the brain of Bombyx mori . Arch. Insect Biochem. Physiol. 61:65–76, 2006. © 2006 Wiley‐Liss, Inc.