Both tissue and serum phospholipases release rat intestinal alkaline phosphatase.
Both tissue and serum phospholipases release rat intestinal alkaline phosphatase.
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组织和血清磷脂酶均释放大鼠肠碱性磷酸酶。
DOI：
10.1152/ajpgi.1990.259.4.g618
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发表时间：
1990
期刊：
影响因子：
--
通讯作者：
Alpers,DH
中科院分区：
文献类型：
--
作者：
Eliakim,R;Becich,MJ;Green,K;Alpers,DH
大鼠肠道碱性磷酸酶（IAP）在刷缘膜酶中是独特的，因为它是双向释放的（管腔和血液），存在于可溶性（血清）或颗粒（细胞）形式。为了阐明膜释放的机制，我们检测了磷脂酰肌醇特异性磷脂酶C （PtdIns-PLC）和血清锚定特异性磷脂酶D （PLD）对各种组织形式IAP溶解度的影响。胞质溶胶IAP的“溶解度”可以部分解释为细胞内PtdIns- plc活性，通过酸性IAP异构体的产生和乙二醇-双（β -氨基乙醚）-N，N，N‘，N’-四乙酸(EGTA)-敏感PtdIns水解来检测。血清污染（富含锚定特异性PLD）是在处理轻度粘膜刮擦过程中发现IAP完全或部分溶解的原因。脂肪喂养后锚定特异性PLD活性增加，释放的IAP与识别ptdins - plc释放的锥虫可变表面糖蛋白磷脂部分的抗血清不发生反应。这些数据与假设是一致的，即从肠细胞分泌到富含磷脂的膜状颗粒后，IAP释放到血清中是由血清锚定特异性PLD介导的。内源性PtdIns-PLC活性和细胞分离过程中发生的锚定特异性PLD污染共同导致了内腔和胞浆中IAP的可溶性形式。
Rat intestinal alkaline phosphatase (IAP) is unique among the brush-border membrane enzymes in that it is released bidirectionally (lumen and blood) and exists in either soluble (serum) or particulate (cellular) form. To elucidate the mechanism of membrane release, we examined the effects of phosphatidylinositol-specific phospholipase C (PtdIns-PLC) and serum anchor-specific phospholipase D (PLD) on the solubility of the various tissue forms of IAP. The "solubility" of cytosol IAP could be explained in part by intracellular PtdIns-PLC activity, detected by production of acidic IAP isomers, and by ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA)-sensitive PtdIns hydrolysis. Contamination with serum (abundant with anchor-specific PLD) was responsible for the complete or partial solubilization of IAP that was found during processing of light mucosal scrapings. Anchor-specific PLD activity was increased after fat feeding, and the IAP released did not react with antiserum that recognizes the PtdIns-PLC-released phospholipid portion of trypanosomal variable surface glycoprotein. These data are consistent with the hypothesis that, after secretion from the enterocyte bound to a phospholipid-rich membranous particle, IAP release into serum is mediated by serum anchor-specific PLD. The soluble forms of IAP in the lumen and the cytosol fraction appear to be due to a combination of endogenous PtdIns-PLC activity and anchor-specific PLD contamination that occurs during cell fractionation.