A comparative study of the activation of protein kinase C α by different diacylglycerol isomers
1999; Portland Press; Volume: 337; Issue: 3 Linguagem: Inglês
10.1042/bj3370387
ISSN1470-8728
AutoresPilar Sánchez‐Piñera, Vicente Micol, Senena Corbalán-Garcı́a, Juan C. G. ÓMEZ-FERNÁNDEZ,
Tópico(s)Analytical Chemistry and Chromatography
ResumoThe lipid activation of protein kinase C α (PKC α) 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 µM 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 α binding studies, performed by differential centrifugation in the presence of 200 µM 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 α was able to bind to membranes containing either 1,2-DOG or 1,3-DOG to the same extent.
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