Isolation of insulin-sensitive phosphatidylinositol-glycan from rat adipocytes. Its impaired breakdown in the streptozotocin-diabetic rat.

摘要: In this study an insulin-sensitive glycophospholipid from rat adipocytes was isolated and partially characterized. A material that activated pyruvate dehydrogenase extracted adipocyte membrane supernatants. Its release stimulated by insulin phosphatidylinositol-specific-phospholipase C its activity destroyed nitrous acid deamination. These findings suggested might stimulate breakdown of a containing inositol glucosamine, as previously reported for some other cell types [Low & Saltiel (1988) Science 239, 268-275]. lipid incorporated [3H]glucosamine, [3H]galactose, [3H]inositol, [3H]myristate whose turnover subsequently intact sequential t.l.c. using acidic solvent system followed basic system. The effects on the in these cells were transient, with maximal at 1 min, there typical concentration-response curve to (0.07 nM-7 nM), being detected over physiological range concentrations. contrast studies cells, appreciable sugar labels. majority [3H]glucosamine [3H]galactose labels cycled through triacylglycerol adipocyte. However, recovered band, major proportion (less than 40%) native label. Digestion purified molecule phosphatidylinositol-specific phospholipase generated both low-Km cyclic AMP phosphodiesterase. Impairment insulin-stimulated streptozotocin-diabetic rats found, consistent impaired activation glucose utilization seen model. suggest stimulates stimulating adipocytes. This compound may serve function precursor intracellular mediators.