Pancreatic Islets Express a Ca2+-independent Phospholipase A2 Enzyme That Contains a Repeated Structural Motif Homologous to the Integral Membrane Protein Binding Domain of Ankyrin*
Pancreatic Islets Express a Ca2+-independent Phospholipase A2 Enzyme That Contains a Repeated Structural Motif Homologous to the Integral Membrane Protein Binding Domain of Ankyrin*
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DOI：
10.1074/jbc.272.17.11118
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发表时间：
1997-04
期刊：
影响因子：
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通讯作者：
Zhongming Ma;S. Ramanadham;Kirsten Kempe;X. Chi;J. Ladenson;J. Turk
中科院分区：
文献类型：
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作者：
Zhongming Ma;S. Ramanadham;Kirsten Kempe;X. Chi;J. Ladenson;J. Turk
胰岛表达钙离子非依赖性磷脂酶A2（CaI-PLA 2）活性，其对卤烯醇内酯自杀底物的抑制敏感，卤烯醇内酯自杀底物也减弱葡萄糖诱导的胰岛磷脂中花生四烯酸的水解和胰岛素分泌。从大鼠胰岛cDNA文库中克隆了一个cDNA，该cDNA编码一种蛋白质，其推导的氨基酸序列为751个残基，与最近从中国仓鼠卵巢细胞中克隆的CaI-PLA 2酶同源。瞬时转染COS-7细胞和中国仓鼠卵巢细胞与克隆的胰岛CaI-PLA 2 cDNA导致细胞CaI-PLA 2活性的增加，这种活性是容易被卤烯醇内酯自杀底物抑制。胰岛CaI-PLA 2的氨基酸残基150-414的结构域由8段长度约为33个氨基酸残基的重复序列基序组成，其与结合微管蛋白和整合膜蛋白的锚蛋白结构域高度同源，所述整合膜蛋白包括调节跨膜离子通量的几种蛋白质。这些发现补充了先前的药理学观察，表明CaI-PLA 2可能参与调节葡萄糖刺激的β细胞中的跨膜离子通量。
Pancreatic islets express a Ca2+-independent phospholipase A2 (CaI-PLA2) activity that is sensitive to inhibition by a haloenol lactone suicide substrate that also attenuates glucose-induced hydrolysis of arachidonic acid from islet phospholipids and insulin secretion. A cDNA has been cloned from a rat islet cDNA library that encodes a protein with a deduced amino acid sequence of 751 residues that is homologous to a CaI-PLA2 enzyme recently cloned from Chinese hamster ovary cells. Transient transfection of both COS-7 cells and Chinese hamster ovary cells with the cloned islet CaI-PLA2 cDNA resulted in an increase in cellular CaI-PLA2 activity, and this activity was susceptible to inhibition by haloenol lactone suicide substrate. The domain of the islet CaI-PLA2 from amino acid residues 150-414 is composed of eight stretches of a repeating sequence motif of approximately 33-amino acid residues in length that is highly homologous to domains of ankyrin that bind both tubulin and integral membrane proteins, including several proteins that regulate ionic fluxes across membranes. These findings complement previous pharmacologic observations that suggest that CaI-PLA2 may participate in regulating transmembrane ion flux in glucose-stimulated β-cells.