2.3.1.291: sphingoid base N-palmitoyltransferase
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For detailed information about sphingoid base N-palmitoyltransferase, go to the full flat file.
Reaction
Synonyms
CerS4, CerS5, LASS5, longevity assurance homolog 5, mammalian ceramide synthase 5
ECTree
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General Information
General Information on EC 2.3.1.291 - sphingoid base N-palmitoyltransferase
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physiological function
CerS5 activity is inhibited in a dominant-negative fashion by co-expression with catalytically inactive CerS5, and isoform CerS2 activity is enhanced by co-expression with a catalytically active form of CerS5 or CerS6. In a constitutive heterodimer comprising CerS5 and CerS2, the activity of CerS2 depends on the catalytic activity of CerS5. CerS dimers are formed upon rapid stimulation of ceramide synthesis by curcumin
physiological function
CerS5 is essential to maintain cellular C16:0 sphingolipid pools in lung, spleen, muscle, liver, and white adipose tissue. In CerS5-deficient mice, glycerophospholipid levels are not altered, while in skeletal muscle, liver, and spleen, C16:0-ceramide levels aere altered independent of feeding conditions. The loss of CerS5 is associated with reduced weight gain and improved systemic health, including maintenance of glucose homeostasis and reduced white adipose tissue inflammation after high fat diet challenge
physiological function
exogenously expressed LASS5 in lung epithelia triggers increased ceramide synthesis, knockdown studies using fumonisin B1 or LASS5 siRNA reduce ceramide synthase activity by 78% or 45%, respectively. Overexpression of LASS5 also reduces phosphatidylcholine synthesis. Maximal inhibition is achieved when LASS5 is coexpressed with a plasmid encoding a neutral sphingomyelinase involved in sphingomyelin hydrolysis
physiological function
inhibition of isoform Cers5 by fuminisin B1 or siRNA suppresses myristate-induced C14-ceramide generation and X-box binding protein XBP1 splicing. Increased XBP1 splicing induces the downstream expression of IL-6 in a isoforms CerS5/6-dependent manner. A myristate-enriched milk fat-based diet, but not a lard-based diet, increases C14-ceramide, XBP1 splicing, and IL-6 expression in vivo
physiological function
ionizing radiation induces de novo synthesis of ceramide to influence HeLa cell apoptosis by specifically activating CerS isoforms 2, 5, and 6 that generate opposing anti- and pro-apoptotic ceramides in mitochondrial membranes. Isoforms CerS5 and CerS6 each confer about 50% of the C16:0 CerS baseline synthetic activity, both are required for ionizing radiation-induced activity. Isoforms CerS2, 5, and 6 might exist as heterocomplexes in HeLa cells
physiological function
Lass5 interacts with succinate dehydrogenase subunit B. The C-terminal fragment of succinate dehydrogenase subunit B is required for the interaction. Lass5 and succinate dehydrogenase subunit B co-localize in COS-7 cells. Lass5 and succinate dehydrogenase subunit B expressions are up-regulated in neuroglioma tissue, and Lass5 or succinate dehydrogenase subunit B expression represses p53 or p21 reporter activity, respectively
physiological function
overexpression of isoform Cers5 leads to accumulation of C16:0 ceramides. Presence of insulin has no effect on sphingomyelins, while palmitate treatment causes a significant decrease in several species, including the predominant C16:0 species. CerS5 knockdown reduces glycogen synthesis in the absence or presence of palmitate. Isoform CerS1 overexpression results in minor upregulation of endogenous CerS5
physiological function
overexpression of LASS elevates the synthesis of (dihydro)ceramides selectively enriched in palmitic acid
physiological function
skeletal muscle from mice deficient of either CerS1 or CerS5 shows reduced caliber sizes of both slow (type 1) and fast (type 2) muscle fibers, fiber grouping, and fiber switch to type 1 fibers. CerS1- and CerS5-deficient mice exhibit reduced twitch and tetanus forces of musculus extensor digitorum longus
physiological function
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exogenously expressed LASS5 in lung epithelia triggers increased ceramide synthesis, knockdown studies using fumonisin B1 or LASS5 siRNA reduce ceramide synthase activity by 78% or 45%, respectively. Overexpression of LASS5 also reduces phosphatidylcholine synthesis. Maximal inhibition is achieved when LASS5 is coexpressed with a plasmid encoding a neutral sphingomyelinase involved in sphingomyelin hydrolysis
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