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Different effects of sphingosine, R59022 and anionic amphiphiles on two diacylglycerol kinase isozymes purified from porcine thymus cytosol
Author(s) -
Sakane Fumio,
Yamada Keiko,
Kanoh Hideo
Publication year - 1989
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(89)81134-2
Subject(s) - diacylglycerol kinase , sphingosine , cytosol , isozyme , biochemistry , microbiology and biotechnology , protein kinase c , phosphatidylserine , biology , gel electrophoresis , enzyme , polyacrylamide gel electrophoresis , chemistry , phospholipid , receptor , membrane
Porcine thymus cytosol contains two immunologically distinct forms of diacylglycerol kinase (DGK) [Yamada, K. and Kanoh, H. (1988) Biochem. J. 255, 601–608]. These 2 DGK species, having apparent molecular masses of 80 and 150 kDa, were purified from the thymus cytosol. Upon sodium dodecyl sulfate‐polyacrylamide gel electrophoresis, the 150‐kDa DGK gave 2 polypeptide bands of 50 and 75 kDa, whereas the 80‐kDa DGK yielded a single protein band. The 80‐kDa DGK was markedly activated by 10–20 μM sphingosine as well as by the known anionic activators such as phosphatidylserine and deoxycholate. In contrast, the 150‐kDa DGK was fully active in the absence of the anionic activators and was strongly inhibited by sphingosine (IC 50 , 20 μM). The putative DGK inhibitor R59022 inhibited the 80‐kDa DGK (IC 50 , 10 μM), but had little effect on the 150‐kDa form. It is therefore clear that in the thymus cytosol there are at least 2 DGK isozymes operating under different control mechanisms.