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Reverse sphingomyelin‐synthase in rat liver chromatin
Author(s) -
Albi Elisabetta,
Lazzarini Remo,
Magni Mariapia Viola
Publication year - 2003
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/s0014-5793(03)00810-x
Subject(s) - sphingomyelin , biochemistry , ceramide , chromatin , sphingomyelin phosphodiesterase , cytosol , biology , atp synthase , chemistry , enzyme , microbiology and biotechnology , membrane , apoptosis , dna
The chromatin phospholipid fraction is enriched in sphingomyelin content which changes during cell maturation and proliferation. Recently, we have demonstrated that the sphingomyelin variations can be due to chromatin neutral sphingomyelinase and sphingomyelin‐synthase activities which differ in pH and K m optima from those present in nuclear membranes. The sphingomyelin can be used also as a source of phosphorylcholine for phosphatidylcholine synthesis by reverse sphingomyelin‐synthase. In the present work we have studied the possible existence of reverse sphingomyelin‐synthase activity in nuclear membrane and chromatin. A very low activity was detected in the homogenate, cytosol and nuclear membrane (0.93±0.14, 2.61±0.33 and 0.87±0.13 pmol/mg protein/min, respectively), whereas the activity present in chromatin was 37.09±2.05 pmol/mg protein/min. The reverse sphingomyelin‐synthase decreases the intranuclear diacylglycerol pool and increases the intranuclear ceramide pool, whereas sphingomyelin‐synthase has an opposite effect. The possible correlation between these enzymes is discussed.