作者: Gerald Gimpl , Falk Fahrenholz
DOI: 10.1046/J.1432-1327.2000.01280.X
关键词: Receptor 、 Biophysics 、 Caveolae 、 Cholesterol 、 Oxytocin receptor 、 GTP' 、 Membrane 、 Agonist 、 Biochemistry 、 Receptor–ligand kinetics 、 Biology
摘要: We analyzed the properties of a G protein-coupled receptor localized in cholesterol-poor vs. cholesterol-rich microdomains plasma membrane. For this purpose, human oxytocin receptor, which is very sensitive against alterations membrane cholesterol level, was stably expressed HEK293 cells. To calculate total number receptors independent ligand binding studies, tagged with an enhanced green fluorescent protein (EGFP) did not change functional receptor. Only 1% were present detergent-insoluble domains. In contrast, employing detergent-free fractionation scheme that preserves activity we detected 10–15% low-density membranes and therein high-affinity state twofold enriched. domains, behaved similar respect to their agonist kinetics GTP sensitivity. However, showed markedly (t ½≈ threefold) stability at 37 °C as compared high-density membranes. Addition fully protected loss function. The importance stabilize supported experiments solubilized receptors. Cholesterol delayed inactivation Chapso. conclusion, data report suggest heptahelical proteins could differ dependence localization different microdomains.