Abdelhaleem M M, Hameed S, Klassen D, Greenberg A H
Manitoba Institute of Cell Biology, University of Manitoba, Winnipeg, Canada.
J Immunol. 1996 Mar 15;156(6):2026-35.
Leukophysin (LKP) is a 28-kDa protein of CTL and U937 monocytic cells that is located in the membrane of high density granules as well as lighter cytoplasmic granules or vesicles. mAbs to KLP were used to clone a full length cDNA clone with an open reading frame coding for a 235-amino acid polypeptide with a molecular mass of 24.3 kDa and two potential transmembrane regions. The nucleotide sequence was highly homologous to the 3' end of human RNA helicase A. Expression of the LKP was confirmed as a reverse transcriptase-PCR product that may be an alternately spliced product of RNA helicase A. The cDNA contained a repetitive motif that was similar to synaptophysin 1, a protein that is important for synaptic vesicle exocytosis. A polyclonal Ab directed against the 17 carboxyl-terminal amino acids of LKP detected the same 28-kDa granule membrane protein as the D545, one of the mAbs used to clone the cDNA. In addition, the D545 mAb reacted strongly with the GST fusion protein of the bacterially expressed LKP cDNA. In confocal immunofluorescence studies, the anti-LKP peptide Ab reacted with granzyme A-negative granules and vesicles in CD8+ CTL lymphocytes from normal and Chediak-Higashi patients. Thus, based on the expression of the C-terminal LKP epitope, vesicular structures an granules have been detected in CTL that are distinct from classical granzyme-containing cytolytic granules.
白细胞生理素（LKP）是一种存在于细胞毒性T淋巴细胞（CTL）和U937单核细胞中的28 kDa蛋白质，位于高密度颗粒膜以及较轻的细胞质颗粒或囊泡中。针对KLP的单克隆抗体被用于克隆一个全长cDNA克隆，该克隆具有一个开放阅读框，编码一个235个氨基酸的多肽，分子量为24.3 kDa，有两个潜在的跨膜区域。核苷酸序列与人RNA解旋酶A的3'端高度同源。LKP的表达被确认为逆转录聚合酶链反应（RT-PCR）产物，它可能是RNA解旋酶A的可变剪接产物。该cDNA包含一个与突触小泡蛋白1相似的重复基序，突触小泡蛋白1是一种对突触小泡胞吐作用很重要的蛋白质。一种针对LKP 17个羧基末端氨基酸的多克隆抗体检测到与用于克隆cDNA的单克隆抗体之一D545相同的28 kDa颗粒膜蛋白。此外，D545单克隆抗体与细菌表达的LKP cDNA的谷胱甘肽S-转移酶（GST）融合蛋白强烈反应。在共聚焦免疫荧光研究中，抗LKP肽抗体与正常和切-东综合征（Chediak-Higashi）患者的CD8+ CTL淋巴细胞中颗粒酶A阴性的颗粒和囊泡发生反应。因此，基于C末端LKP表位的表达，在CTL中检测到了与经典的含颗粒酶的溶细胞颗粒不同的囊泡结构和颗粒。
