Mammalian diacylglycerol kinases: Molecular interactions and biological functions of selected isoforms

The mammalian diacylglycerol kinases (DGK) are a group of enzymes having important roles in regulating many biological processes. Both the product and the substrate of these enzymes, i.e. diacylglycerol and phosphatidic acid, are important lipid signalling molecules. Each DGK isoforms appears to have a distinct biological function as a consequence of its location in the cell and/or the proteins with which it associates. This review discusses three of the more extensively studied forms of this enzyme, DGK alpha, DGK epsilon, and DGK zeta. DGK alpha has an important role in immune function and its activity is modulated by several mechanisms. DGK epsilon has several unique features among which is its specificity for arachionoyl-containing substrates, suggesting its importance in phosphatidylinositol cycling. DGK zeta is expressed in many tissues and also has several mechanisms to regulate its functions. It is localized in several subcellular organelles, including the nucleus. The current state of our understanding of the properties and functions of these proteins is reviewed. (C) 2009 Elsevier B.V. All rights reserved.