Osmotic shock-dependent redistribution of diacylglycerol kinase ?1 to non-ionic detergent-resistant membrane via pleckstrin homology and C1 domains.

Journal of biochemistry

PubMedID: 23127959

Matsutomo D, Isozaki T, Sakai H, Sakane F. Osmotic shock-dependent redistribution of diacylglycerol kinase ?1 to non-ionic detergent-resistant membrane via pleckstrin homology and C1 domains. J Biochem. 2013;153(2):179-90.
Diacylglycerol kinase (DGK) participates in regulating the intracellular concentrations of two bioactive lipids, diacylglycerol and phosphatidic acid. DGK?1 is a type II isozyme that contains a pleckstrin homology (PH) domain and a pair of C1 domains at the N-terminus and separated catalytic domains (catalytic subdomain-a and b). We previously reported that DGK?1 expressed in COS-7 cells is translocated from the cytoplasm to punctate granules that partially include endosomes in response to stress stimuli such as osmotic shock. However, the biochemical properties of the stress-dependent behaviour of DGK?1 remain unknown. Here, we have found that DGK?1 is redistributed from the cytosol to the non-ionic detergent (Nonidet P-40)-resistant membrane (DRM) in response to osmotic shock. Our results strongly suggested that the Nonidet P-40 insolubility of DGK?1 is due to neither cytoskeleton localization nor lipid raft association, implying that DGK?1 is distributed to detergent-resistant membrane microdomains that have a low lipid-to-protein ratio. We revealed, using a series of DGK?1 deletion mutants, that the PH and C1 domains play a pivotal role in osmotic shock-dependent DRM redistribution, whereas catalytic subdomain-a negatively regulates the event.