Diacylglycerol kinase
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Diacylglycerol kinase (DGK) is a family of enzymes that catalyzes the conversion of diacylglycerol (DAG) to phosphatidic acid (PA) utilizing ATP as a source of the phosphate. In non-stimulated cells, DGK activity is low allowing DG to be used for glycerophospholipid biosynthesis but on receptor activation of the phosphoinositide pathway, DGK activity increases driving the conversion of DAG to PA. As both lipids are thought to function as bioactive lipid signaling molecules with distinct cellular targets, DGK therefore occupies an important position, effectively serving as a switch by terminating the signalling of one lipid while simultaneously activating signalling by another.[1]
[edit] DGK Isoforms
Currently, nine members of the DGK family have been cloned and identified. Although all family members have conserved catalytic domains and two cysteine rich domains, they are further classified into five groups according to the presence of additional functional domains and substrate specificity.[2] These are as follows:
- Type 1 - DGK-α, DGK-β, DGK-γ - contain EF-hand motifs and a recoverin homology domain
- Type 2 - DGK-δ, DGK-η - contain a pleckstrin homology domain
- Type 3 - DGK-ε - has specificity for arachidonate-containing DAG
- Type 4 - DGK-ζ, DGK-ι - contain a MARCKS homology domain, ankyrin repeats and a nuclear localisation signal
- Type 5 - DGK-θ - contains a third cysteine-rich domain, a pleckstrin homology domain and a proline rich region
[edit] References
- ^ Merida, I, Avila-Flores, A, and Merino, E. (2008). "Diacylglycerol kinases: at the hub of cell signalling.". Biochem. J. 409 (1): 1-18. PMID 18062770.
- ^ Van Blitterswijk, W.J., and Houssa, B. (2000). "Properties and functions of diacylglycerol kinases.". Cellular Signaling 1: 595-605. PMID 11080611.
