Herbette L G, Favreau C, Segalman K, Napolitano C A, Watras J
J Biol Chem. 1984 Jan 25;259(2):1325-35.
The interaction of micromolar concentrations of palmitic and oleic acids with the sarcoplasmic reticulum membrane was studied by electron microscopic techniques in an attempt to define their different effects on ATP-induced calcium sequestration in sarcoplasmic reticulum vesicles. Oleic acid had a concentration-dependent effect on the morphology of sarcoplasmic reticulum vesicles, promoting vesicle fusion and eventual solubilization. Palmitic acid did not alter the morphology of sarcoplasmic reticulum, but its probable site(s) of interaction could be determined. In the presence of palmitic acid, large lamellar structures that formed external to sarcoplasmic reticulum vesicles are probably composed of pure palmitic acid and/or palmitic acid/phospholipid mixed "micelles," but internalization of palmitic acid into sarcoplasmic reticulum vesicles was not detected. Palmitic acid reduced the phospholipid content of sarcoplasmic reticulum membranes with a preservation of the average interparticle protein spacing as observed in freeze-fracture electron micrographs. Thus, palmitic acid appears to be incorporated into the sarcoplasmic reticulum lipid bi-layer. Oleic acid inhibition of ATP-induced calcium sequestration by sarcoplasmic reticulum vesicles is probably caused by net permeability changes of the membrane. A structural mechanism for palmitic acid stimulation of ATP-induced calcium sequestration is proposed in light of the probable insertion of palmitic acid into the sarcoplasmic reticulum lipid bilayer.
运用电子显微镜技术研究了微摩尔浓度的棕榈酸和油酸与肌浆网膜的相互作用，旨在确定它们对肌浆网囊泡中ATP诱导的钙螯合作用的不同影响。油酸对肌浆网囊泡的形态有浓度依赖性影响，促进囊泡融合并最终使其溶解。棕榈酸不会改变肌浆网的形态，但可以确定其可能的相互作用位点。在棕榈酸存在的情况下，在肌浆网囊泡外部形成的大的层状结构可能由纯棕榈酸和/或棕榈酸/磷脂混合“微团”组成，但未检测到棕榈酸内化到肌浆网囊泡中。棕榈酸降低了肌浆网膜的磷脂含量，同时在冷冻断裂电子显微镜照片中观察到颗粒间平均蛋白质间距保持不变。因此，棕榈酸似乎被整合到肌浆网脂质双层中。油酸对肌浆网囊泡中ATP诱导的钙螯合作用的抑制可能是由膜的净通透性变化引起的。鉴于棕榈酸可能插入肌浆网脂质双层，提出了棕榈酸刺激ATP诱导的钙螯合作用的结构机制。
