title: Presence of phosphatidylserine synthesizing enzymes in triton insoluble floating fractions from cerebrocortical plasma membranes: do phosphatidylserine synthesizing enzymes in plasma membrane microdomains play a role in signal transduction?
abstract: Mammals synthesize phosphatidylserine (PS), a binding PKC molecule, by exchanging the nitrogen base of phosphatidylethanolamine or phosphatidylcholine with free serine. Serine base exchange enzyme (SBEE) was found in Triton insoluble floating fractions (TIFFs) from rat cerebellum which contained PKC. Consequently, SBEE might modulate PS levels in the PKC binding area (Buratta et al., J Neurochem 103:942-951, 2007). In the present study, we determined whether SBEE and PKC were localised in rat cerebral cortex TIFFs (cx-TIFFs) and in rat cerebrocortical plasma membrane-TIFFs (PM-TIFFs) which are more directly involved in signal transduction than intracellular membranes. Cx-and PM-TIFFs expressed SBEE activity and contained PKC. SBEE used ethanolamine as free exchanging base which may modulate PS level in the PKC binding area, transforming PS into PE and vice versa. The slight decrease in [(14)C]serine incorporation in the presence of choline indicated the existence of a SBEE isoform which may play a peculiar role in this brain area.
authors.affiliation: Department of Experimental Medicine and Biochemical Sciences, University of Perugia, Via del Giochetto, 06127 Perugia, Italy.
authors.forename: Sandra
authors.initials: S
authors.lastname: Buratta
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Ferrara
authors.forename: Rita
authors.initials: R
authors.lastname: Mozzi
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002462:Cell Membrane / Q000378:metabolism; D002540:Cerebral Cortex / Q000378:metabolism*; D004798:Enzymes / Q000378:metabolism*; D010718:Phosphatidylserines / Q000096:biosynthesis*; D051381:Rats; D015398:Signal Transduction
chemical_list: D004798:Enzymes; D010718:Phosphatidylserines