InterPro domain: IPR001206

The DAG-kinase catalytic domain or DAGKc domain is present in mammalian lipid kinases, such as diacylglycerol (DAG), ceramide and sphingosine kinases, as well as in related bacterial proteins [ 1 , 2 ]. Eukaryotic DAG-kinase ( 2.7.1.107 ) catalyses the phosphorylation of DAG to phosphatidic acid, thus modulating the balance between the two signaling lipids. At least ten different isoforms have been identified in mammals, which form 5 groups characterised by different functional domains, such as the calcium-binding EF hand (see PDOC00018 ), PH (see PDOC50003 ), SAM (see PDOC50105 ) , DAG/PE-binding C1 domain (see PDOC00379 ) and ankyrin repeats (see PDOC50088 ) [ 3 ].

In bacteria, an integral membrane DAG kinase forms a homotrimeric protein that lacks the DAGKc domain (see PDOC00820 ). In contrast, the bacterial yegS protein is a soluble cytosolic protein that contains the DAGKc domain in the N-terminal part. YegS is a lipid kinase with two structural domains, wherein the active site is located in the interdomain cleft, C-terminal to the DAGKc domain which forms an alpha/beta fold [ 4 ]. The tertiary structure resembles that of NAD kinases and contains a metal-binding site in the C-terminal region [ 4 , 4 ].

This domain is usually associated with an accessory domain (see IPR000756 ).

1. Molecular cloning of a novel diacylglycerol kinase isozyme with a pleckstrin homology domain and a C-terminal tail similar to those of the EPH family of protein-tyrosine kinases. J. Biol. Chem. 271, 8394-401
2. Crystal structure of YegS, a homologue to the mammalian diacylglycerol kinases, reveals a novel regulatory metal binding site. J. Biol. Chem. 282, 19644-52
3. Diacylglycerol kinases: why so many of them? Biochim. Biophys. Acta 1771, 793-806
4. Molecular determinants for interfacial binding and conformational change in a soluble diacylglycerol kinase. J. Biol. Chem. 284, 7246-54