Specificity of the fatty acyl moieties of diacylglycerol for the activation of calcium-activated, phospholipid-dependent protein kinase.

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.