Young J D, Podack E R, Cohn Z A
J Exp Med. 1986 Jul 1;164(1):144-55. doi: 10.1084/jem.164.1.144.
Histocompatibility-restricted cytotoxic T lymphocytes produce circular lesions on target cell membranes. The pore-forming protein (PFP or perforin 1) that forms these membrane lesions has been purified from lymphocytes. At 37 degrees C, in the presence of Ca2+, this protein polymerizes into a supramolecular tubular complex of Mr greater than 10(6) that partially resists dissociation by SDS and reducing agents. It incorporates spontaneously into planar lipid bilayers during polymerization to form nonselective ion channels, showing heterogeneous size distribution, the smallest conductance per unit being identified as 400 pS in 0.1 M NaCl. PFP/P1 that had been assembled in lipid vesicles before incorporation into planar bilayer show much larger single channel conductance, ranging from 1 to 6 nS in 0.1 M NaCl, suggesting that PFP/P1 may assume multiple functional sizes in proportion to its state of polymerization. The reconstituted channels are relatively voltage-insensitive, with most channels persisting in the open state for seconds to minutes. Nucleated cells are rapidly depolarized by this protein. The purified protein lyses a variety of tumor cells. Polymerization and functional channel activity are absolutely Ca2+-dependent. The activity of this protein may play a direct role in T lymphocyte-mediated cytolysis.
组织相容性限制的细胞毒性T淋巴细胞在靶细胞膜上产生圆形损伤。形成这些膜损伤的成孔蛋白（PFP或穿孔素1）已从淋巴细胞中纯化出来。在37摄氏度、存在Ca2+的情况下，这种蛋白质聚合成一种分子量大于10^6的超分子管状复合物，该复合物部分抵抗SDS和还原剂的解离。在聚合过程中，它会自发地整合到平面脂质双分子层中形成非选择性离子通道，显示出异质的大小分布，在0.1 M NaCl中每单位最小电导率被确定为400 pS。在整合到平面双分子层之前已组装在脂质囊泡中的PFP/P1显示出大得多的单通道电导率，在0.1 M NaCl中范围为1至6 nS，这表明PFP/P1可能根据其聚合状态呈现多种功能大小。重构的通道对电压相对不敏感，大多数通道在开放状态下持续数秒至数分钟。有核细胞会被这种蛋白质迅速去极化。纯化的蛋白质可裂解多种肿瘤细胞。聚合和功能性通道活性绝对依赖于Ca2+。这种蛋白质的活性可能在T淋巴细胞介导的细胞溶解中起直接作用。
