5-lipoxygenase and 5-lipoxygenase-activating protein are localized in the nuclear envelope of activated human leukocytes.
5-lipoxygenase and 5-lipoxygenase-activating protein are localized in the nuclear envelope of activated human leukocytes.
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5-脂氧合酶和5-脂氧合酶激活蛋白定位于活化的人白细胞的核包膜中。
DOI：
10.1084/jem.178.6.1935
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发表时间：
1993-12-01
期刊：
影响因子：
--
通讯作者：
Singer II
中科院分区：
文献类型：
--
作者：
Woods JW;Evans JF;Ethier D;Scott S;Vickers PJ;Hearn L;Heibein JA;Charleson S;Singer II
本文用超薄冰冻切片免疫电子显微镜标记和亚细胞分离技术，测定了静息和离子载体激活的人白细胞中5-脂氧合酶(5-LO)和5-脂氧合酶激活蛋白(FLAP)的细胞内分布。5-LO是一种78kD的蛋白质，催化花生四烯酸转化为白三烯。Flat是一种18kD的膜结合蛋白，对细胞中白三烯的合成是必不可少的。作为对离子载体刺激的响应，5-LO从细胞匀浆中的可溶部分转移到可沉淀部分。在激活的白细胞中，FLOW和5-LO均定位于核膜的管腔内。在任何其他细胞室或沿质膜均未检测到这两种蛋白质。在静息细胞中，瓣的分布与在激活细胞中观察到的相同。此外，亚细胞分离技术显示，83%的免疫印迹可检测到的翻盖蛋白和大约%的翻盖配体结合活性存在于核膜部分。分离对照表明，在核膜组分中不能检测到由单抗PMN13F6检测到的质膜标志物。与FLOW相反，静息细胞中的5-LO不能沿核膜显示。除核常染色质区弱标记外，5-LO在其他细胞室均不能轻易检测到。这些结果表明，核膜是5-LO和FLAW代谢花生四烯酸的细胞内部位，中性粒细胞和单核细胞的离子载体激活导致5-LO从一个不可沉积的位置移位到核被膜上。
The intracellular distribution of the enzyme 5-lipoxygenase (5-LO) and 5-lipoxygenase-activating protein (FLAP) in resting and ionophore- activated human leukocytes has been determined using immuno- electronmicroscopic labeling of ultrathin frozen sections and subcellular fractionation techniques. 5-LO is a 78-kD protein that catalyzes the conversion of arachidonic acid to leukotrienes. FLAP is an 18-kD membrane bound protein that is essential for leukotriene synthesis in cells. In response to ionophore stimulation, 5-LO translocates from a soluble to a sedimentable fraction of cell homogenates. In activated leukocytes, both FLAP and 5-LO were localized in the lumen of the nuclear envelope. Neither protein could be detected in any other cell compartment or along the plasma membrane. In resting cells, the FLAP distribution was identical to that observed in activated cells. In addition, subcellular fractionation techniques showed > 83% of immunoblot-detectable FLAP protein and approximately 64% of the FLAP ligand binding activity was found in the nuclear membrane fraction. A fractionation control demonstrated that a plasma membrane marker, detected by a monoclonal antibody PMN13F6, was not detectable in the nuclear membrane fraction. In contrast to FLAP, 5-LO in resting cells could not be visualized along the nuclear envelope. Except for weak labeling of the euchromatin region of the nucleus, 5-LO could not be readily detected in any other cellular compartment. These results demonstrate that the nuclear envelope is the intracellular site at which 5-LO and FLAP act to metabolize arachidonic acid, and that ionophore activation of neutrophils and monocytes results in the translocation of 5-LO from a nonsedimentable location to the nuclear envelope.