STUDIES ON ANIMAL CELL SURFACE PHOSPHATIDYLSERINE-FLIPPASE

动物细胞表面磷脂酰丝氨酸翻转酶的研究

基本信息

批准号：
05680570
负责人：
KOBAYASHI Toshihide
金额：
$ 1.34万
依托单位：
TOHOKU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1994
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-05680570/
关键词：
Flip-flop Flippase Membrane lipid asymmetry Endocytosis CHO cell Plasma membrane Fluorescent lipid analog Phosphatidylserine CHO

项目摘要

Flippases are membrane proteins which catalyze transbilayr movement (flip-flop) of membrane lipids. Structure of flippases are not well understood. Up to now several flippases have been reported. Among them, plasma membrane flippase has been studied well. This protein catalyzes transbilayr movement of cell surface phosphatidylserine in ATP-dependent manner. The function of cell surface flippase is not known. It has been proposed that plasma membrane flippase is involved in the maintenance of plasma membrane lipid asymmetry and/or endocytosis.Previously we have suggested that exogenous phosphatidylserine is internalized via cell surface flippase (Kobayashi, T.and Arakawa, Y.(1991) J.CellBiol., 113,235-244). In the course of studying the internalization of exogenous phosphatidylserine into cells, we found that phosphatidylserine which has unsaturated fatty acid has cytotoxicity. Assuming that phosphatidylserine-resistant cells are defective in the first step of internalization of phosphatidylserine i.e.flip-flop on the plasma membrane, we have isolated phosphatidylserine-resistant mutants. 40% of phosphatidylserine-resistant cells were defective in transbilayr movement of cell surface phosphatidylserine. Using these mutants, we have measured 1) asymmetry of membrane lipids and 2) activity of endocytosis. Phosphatidylserine-resistant mutants retained lipid asymmetry. On the other hand, endocytosis activity of mutant cells, measured by using lucifer yellow and horse radish peroxidase (HRP), was about half of that of wild type CHO cells. Our results suggest that flip-flop of membrane phospholipids are involved in endocytosis.

Flippases是膜蛋白，可催化膜脂质的转贝运动（触发）。 Flippases的结构尚不清楚。到目前为止，已经报道了几条爆破。其中，质膜氟脂酶已经进行了很好的研究。该蛋白质催化细胞表面磷脂酰丝氨酸的转贝运动以ATP依赖性方式。细胞表面Flippase的功能尚不清楚。有人提出，质膜flippase参与质膜脂质不对称和/或内吞作用的维持。我们已经提出，外源性磷脂酰丝氨酸是通过细胞表面氟脂酶内化的（kobayashi，t.andarakawa，t.ankawa，arakawa，y。y.（19911）。在研究外源性磷脂酰丝氨酸内化到细胞中的过程中，我们发现磷脂酰丝氨酸的磷酸甲酯具有不饱和脂肪酸的细胞毒性。假设在磷脂酰丝氨酸内部化的第一步，即质膜上的磷脂酰丝氨酸，我们已经分离出抗磷脂酰丝氨酸的突变体。 40％的磷脂酰丝氨酸耐药细胞在细胞表面磷脂酰丝氨酸的转贝运动中有缺陷。使用这些突变体，我们测量了1）膜脂质的不对称性和2）内吞作用的活性。磷脂酰丝氨酸耐药突变体保留脂质不对称。另一方面，通过使用露西夫黄和马萝卜过氧化物酶（HRP）测量的突变细胞的内吞作用活性约为野生型CHO细胞的一半。我们的结果表明，膜磷脂的触发器参与内吞作用。