Abstract
Phosphorylations of at least four proteins, approximately 32, 28, 25 and 21 kDa, were promoted in the brain-corpus cardiacum-corpus allatum (brain-CC-CA) complex of Bombyx mori with 2 mM carbachol (acetylcholine agonist). These phosphorylations depended on carbachol concentrations in the range of 10 μM-1 mM, and occurred within 5 min. Two millimolar muscarine, but not nicotine, promoted phosphorylations of the four proteins, and the phosphorylations were inhibited with 5 mM atropine (muscarinic acetylcholine antagonist), indicating the involvement of the muscarinic acetylcholine receptor. Inhibitory effects of a calmodulin antagonist and a specific inhibitor of protein kinase C on the carbachol-induced protein phosphorylation suggested that the 25 and 21 kDa proteins were phosphorylated by protein kinase C and a calcium/calmodulin dependent protein kinase, respectively, and that both phosphoproteins were localized in the CC-CA complex. Further, the carbachol-induced PTTH release was observed from 1 min to 5 min and was dependent on carbachol concentrations in the range of 10 μM-1 mM, corresponding to conditions for the carbachol-induced protein phosphorylations.
