Specificity of the Fatty Acyl Moieties of Diacylglycerol for the Activation of Calcium-Activated, Phospholipid-Dependent Protein Kinase1

Abstract

The specificity of the fatty acyl moieties of diacylglycerol for the activation of Ca ^a2+− activated, phospholipid-dependent protein kinase was investigated. Diacyiglycerol has been previously shown to activate this enzyme by increasing the affinity for Ca ²⁺ and phospholipid, both of which are indispensable for the enzyme activation. Di acylglycerols containing at least one unsaturated fatty acid at either position I or 2 are fully active in this capacity, irrespective of the chain length of the other fatty acyl moiety in the range tested, C ₂ to C ₁₈ Diacylglycerols containing two saturated fatty acids such as dipalmitin and distearin are far less effective. Mono- and triacyl glycerols and free fatty acids are totally inactive, indicating that the diacylglycerol structure is essential.