A comparative study of the activation of protein kinase C alpha by different diacylglycerol isomers.
The lipid activation of protein kinase C alpha (PKC alpha) has been studied by comparing the activation capacity of different 1, 2-diacylglycerols and 1,3-diacylglycerols incorporated into mixed micelles or vesicles. Unsaturated 1,2-diacylglycerols were, in general, more potent activators than saturated ones when 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoserine (POPS)/Triton X-100 mixed micelles and pure POPS vesicles were used. In contrast, these differences were not observed when 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC)/POPS (4:1, molar ratio) vesicles were used. Diacylglycerols bearing short fatty acyl chains showed a very high activation capacity, however, the capacity was less in mixed micelles. Furthermore, 1, 2-diacylglycerols had a considerably higher activating capacity than 1,3-diacylglycerols in POPS/Triton X-100 mixed micelles and in POPC/POPS vesicles. However, the differences between the two types of diacylglycerols were smaller when pure POPS vesicles were used. Differential scanning calorimetry (DSC) showed that POPC/POPS membrane samples containing diacylglycerols had endothermic transitions in the presence of 200 microM Ca2+ and 5 mM Mg2+. Transitions were not detected when using pure POPS vesicles due to the formation of dehydrated phases as demonstrated by FTIR (Fourier-transform infrared) spectroscopy. PKC alpha binding studies, performed by differential centrifugation in the presence of 200 microM Ca2+ and 5 mM Mg2+, showed that 1,2-sn-dioleoylglycerol (1, 2-DOG) was more effective than 1,3-dioleoylglycerol (1,3-DOG) in promoting binding to POPC/POPS vesicles. However, when pure POPS vesicles were used, PKC alpha was able to bind to membranes containing either 1,2-DOG or 1,3-DOG to the same extent.
Sánchez-Piñera
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Departamento de Bioqu approximately ímica y Biolog approximately ía Molecular (A), Edificio de Veterinaria, Universidad de Murcia, Apartado Postal 4021, E-30080, Murcia, Spain.
Micol
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Corbalán-García
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Gómez-Fernández
J C
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D002118:Calcium / Q000737:chemistry; D004789:Enzyme Activation; D005227:Fatty Acids / Q000737:chemistry*; D005990:Glycerol / Q000031:analogs & derivatives / Q000737:chemistry*; D007527:Isoenzymes / Q000737:chemistry*; D008274:Magnesium / Q000737:chemistry; D008567:Membranes, Artificial; D017830:Octoxynol; D010713:Phosphatidylcholines; D010718:Phosphatidylserines; D011493:Protein Kinase C / Q000737:chemistry*; D051571:Protein Kinase C-alpha; D017550:Spectroscopy, Fourier Transform Infrared; D013329:Structure-Activity Relationship
D005227:Fatty Acids; D007527:Isoenzymes; D008567:Membranes, Artificial; D010713:Phosphatidylcholines; D010718:Phosphatidylserines; C050294:1-palmitoyl-2-oleoylglycero-3-phosphoserine; D017830:Octoxynol; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha; D008274:Magnesium; D005990:Glycerol; D002118:Calcium; C028694:1-palmitoyl-2-oleoylphosphatidylcholine