AN ISOFORM OF THE PHOSPHATIDYLINOSITOL-TRANSFER PROTEIN TRANSFERS SPHINGOMYELIN AND IS ASSOCIATED WITH THE GOLGI SYSTEM
AN ISOFORM OF THE PHOSPHATIDYLINOSITOL-TRANSFER PROTEIN TRANSFERS SPHINGOMYELIN AND IS ASSOCIATED WITH THE GOLGI SYSTEM
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DOI：
10.1042/bj3100643
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发表时间：
1995-09-01
影响因子：
4.1
通讯作者：
SNOEK, GT
中科院分区：
文献类型：
--
作者：
DEVRIES, KJ;HEINRICHS, AAJ;SNOEK, GT
在牛脑的细胞质部分中鉴定出磷脂酰肌醇转移蛋白（PI-TP）的同工型。这种蛋白质被命名为 PI-TP beta，表观分子质量为 36 kDa，等电点为 5.4。 N 端氨基酸序列（21 个残基）与牛脑 PI-TP 的氨基酸序列有 90% 相似，因此称为 PI-TP α。 （分子量 35 kDa，等电点 5.5）。正如对 PI-TP α 所观察到的，PI-TP β 对磷脂酰肌醇的偏好明显高于对磷脂酰胆碱的偏好。此外，它对鞘磷脂表现出高转移活性。 PI-TP α 完全缺乏这种活性。通过间接免疫荧光，我们证明，在瑞士小鼠 3T3 成纤维细胞中，PI-TP β 优先与高尔基体系统相关，而 PI-TP α 主要存在于细胞质和细胞核中。在胞质耗尽的 HL60 细胞中，PI-TP α 和 PI-TP β 在重建鸟苷 5'-γ-硫代]三磷酸介导的磷脂酶 C β 活性方面同样有效。
An isoform of the phosphatidylinositol-transfer protein (PI-TP) was identified in the cytosol fraction of bovine brain. This protein, designated PI-TP beta, has an apparent molecular mass of 36 kDa and an isoelectric point of 5.4. The N-terminal amino acid sequence (21 residues) is 90% similar to that of bovine brain PI-TP, henceforth designated PI-TP alpha. (molecular mass 35 kDa and pI 5.5). As observed for PI-TP alpha, PI-TP beta has a distinct preference for phosphatidylinositol over phosphatidylcholine. addition, it expresses a high transfer activity towards sphingomyelin. PI-TP alpha lacks this activity completely. By indirect immunofluorescence we demonstrated that, in Swiss mouse 3T3 fibroblasts, PI-TP beta is preferentially associated with the Golgi system whereas PI-TP alpha is predominantly present in the cytoplasm and the nucleus. In cytosol-depleted HL60 cells, both PI-TP alpha and PI-TP beta were equally effective at reconstituting guanosine 5'-[gamma-thio]triphosphate-mediated phospholipase C beta activity.