Molecular characterization of a membrane-bound cGMP dependent protein kinase from the silk moth Bombyx mori

The cGMP signalling pathway has been suggested to be involved in the signal transduction of various physiological functions in insects; olfaction, antidiuresis and eclosion. However, the cGMP signalling mechanism has remained elusive. We isolated two cDNAs of the cGMP dependent protein kinase, designated BmPKG-Ialpha and BmPKG-Ibeta. The deduced amino acid sequences indicate that both BmPKG-Ialpha and BmPKG-Ibeta appear to consist of an amino terminal region, a cGMP binding domain and a protein kinase domain. Transcripts of BmPKG-Ialpha and BmPKG-Ibeta were detected in various tissues: flight muscles, antennae, midgut, legs, head, thoracic ganglia and Malphighian tubules. Recombinant BmPKG-Ialpha bound to lipid membranes, while BmPKG-Ialpha with a deleted amino terminal region failed to bind to lipid membranes.