Vesicle-mediated transfer of phospholipids to plasma membrane during cell aggregation of Dictyostelium discoideum.
Vesicle-mediated transfer of phospholipids to plasma membrane during cell aggregation of Dictyostelium discoideum.
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盘基网柄菌细胞聚集过程中囊泡介导的磷脂向质膜的转移。
DOI：
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发表时间：
1981
影响因子：
4.8
通讯作者：
C. Siu
中科院分区：
文献类型：
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作者：
N. D. de Silva;C. Siu
我们先前已经报道，在盘基网柄藻发育过程中，在趋化迁移开始时，磷脂的合成增加4倍，并且新合成的磷脂优先掺入质膜（De Silva，N. S.及Siu，C-H.（1980）J.Biol.Chem.255，8489-8496）。为了验证这一假设，即磷脂的快速转移到质膜介导的囊泡，我们分离出富含磷脂的囊泡从细胞在6小时的发展。这些囊泡的平均直径为0.35微米。它们以1.097 g/cm 3的密度成带，并且它们具有2.25的磷脂：蛋白质（w/w）比。这些囊泡中的主要磷脂类是磷脂酰乙醇胺和磷脂酰胆碱。在使用[3 H]甘油的脉冲标记研究中，这些低密度囊泡具有最高的磷脂比活性，约为6小时质膜的3倍。发现几乎80%的掺入放射性与磷脂酰乙醇胺和磷脂酰胆碱有关。当细胞追逐冷前体脉冲标记后，这些囊泡的比活性下降了近20倍，在90分钟内，而质膜表现出2.5倍的增加，在60分钟。此外，秋水仙素7小时细胞抑制新合成的磷脂易位到质膜。低密度囊泡被发现在preaggregation阶段的细胞或aggregateless突变体WL 3中的量大大减少。这些结果表明，新合成的磷脂从其合成位点转移到质膜可能是通过一类特殊的富含磷脂的囊泡发生的。
We have previously reported that synthesis of phospholipids increases 4-fold at the onset of chemotactic migration during development of Dictyostelium discoideum and that the newly synthesized phospholipids are preferentially incorporated into the plasma membrane (De Silva, N. S. and Siu, C-H. (1980) J. Biol. Chem. 255, 8489-8496). To test the hypothesis that the rapid transfer of phospholipids to the plasma membrane is mediated by vesicles, we isolated phospholipid-rich vesicles from cells at 6 h of development. These vesicles had an average size of 0.35 micrometer in diameter. They banded at a density of 1.097 g/cm3 and they had a phospholipid: protein (w/w) ratio of 2.25. The predominant classes of phospholipids in these vesicles were phosphatidylethanolamine and phosphatidylcholine. In pulse-labeling studies using [3H]glycerol, these low density vesicles had the highest phospholipid-specific activity, which was about 3 times higher than that of 6-h plasma membranes. Almost 80% of the incorporated radioactivity was found to be associated with phosphatidylethanolamine and phosphatidylcholine. When cells were chased with cold precursor after pulse labeling, the specific activity of these vesicles dropped by almost 20-fold in 90 min, while plasma membranes showed a 2.5-fold increase in 60 min. Addition of colchicine to 7-h cells inhibited the translocation of newly synthesized phospholipids to the plasma membrane. The low density vesicles were found in much reduced amounts in preaggregation stage cells or the aggregateless mutant WL3. These results indicate that transfer of newly synthesized phospholipids from their site of synthesis to the plasma membrane probably occurs through a special class of phospholipid-rich vesicles.