Ca 2+/calmodulin and Ca 2+/phospholipid-dependent protein kinases in the neural tissue of the honeybee Apis mellifera

Abstract

The Ca 2+/calmodulin and Ca 2+/phospholipid-dependent protein kinases have been purified and characterized from neural tissue of the honeybee Apis mellifera. Ca 2+/calmodulin-dependent protein kinase appeared as a multisubunit complex composed of three subunits that co-migrate with kinase activity during all purification steps. The three subunits had molecular weights of 52,000, 57,000 and 60,000, termed α, β′ and β, respectively. The α and β subunits are distinct peptides whereas β′ may have been generated from β by proteolysis. The Ca 2+/calmodulin-dependent protein kinase required 0.1 μM calmodulin and about 1 μM Ca 2+ for half-maximal activation. The Ca 2+/phospholipid-dependent protein kinase (protein kinase C) was purified from honeybee neural tissue by using DEAE-Sephacel and phosphatidylserine-affinity chromatography. The molecular weight of the protein kinase C was about 80,000 as estimated by gelfiltration. Subjection to SDS-PAGE gave a single band with M r = 80,000 , indicating that the enzyme exists as a monomer. The enzyme was fully activated by diacylglycerol in the presence of phospholipid and Ca 2+.