Cytoplasmic Proteins, Association with Phospholipid Vesicles and Its Dependency on Cholesterol

[摘要] References(29)Since the plasticity of the plasma membrane is correlated with changes in its dynamic behavior and biological functions, the content of cholesterol in this membrane is thought to have an important role in the regulation of cell metabolism. The research reported here was done to clarify the role of cholesterol in the interaction of the innersurface of plasma mem-brane with cytoplasmic proteins in relation to the regulatory mechanism of signal transduction.Many cytoplasmic proteins of EATC or rat liver cells were found to associate with DPPC liposomes and they induced a transient increase in membrane permeability at the phase transition temperature of the liposomal lipid. The association and the permeability increase were inhibited by the introduction of cholesterol into DPPC liposomes, and the sensitivity of individual proteins to the action of cholesterol differed. F-actin, but not G-actin, associated selectively with the liposomes. Also, the main endothermic peak of the unilamellar DPPC liposomes was shifted from 37°C to 43°C by this protein association, evidence of transformation from a unito multi-lamellar structure.The introduction of cholesterol into the liposomal membrane caused a reduction in the energy content of the phase transition and in the inhibition of protein-membrane interaction. We concluded that the cholesterol in the plasma membrane contributes to the regulation of cell surface signal trans-duction.

[学科分类] 分子生物学，细胞生物学和基因