Specificity of the Fatty Acyl Moieties of Diacylglycerol for the Activation of Calcium-Activated, Phospholipid-Dependent Protein Kinase

Abstract

The specificity of the fatty acyl moieties of diacylglycerol for the activation of Ca²⁺-activated, phospholipid-dependent protein kinase was investigated. Diacylglycerol has been previously shown to activate this enzyme by increasing the affinity for Ca²⁺ and phospholipid, both of which are indispensable for the enzyme activation. Diacylglycerols containing at least one unsaturated fatty acid at either position 1 or 2 are fully active in this capacity, irrespective of the chain length of the other fatty acyl moiety in the range tested, C₂ to C₁₈. Diacylglycerols containing two saturated fatty acids such as dipalmitin and distearin are far less effective. Mono- and triacylglycerols and free fatty acids are totally inactive, indicating that the diacylglycerol structure is essential.