Tumor cell membrane cathepsin B
Tumor cell membrane cathepsin B
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DOI：
10.1515/bchm.1998.379.8-9.1093
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发表时间：
1998-08-01
影响因子：
3.7
通讯作者：
Sloane, BF
中科院分区：
文献类型：
--
作者：
Moin, K;Cao, L;Sloane, BF
溶酶体半胱氨酸肽酶组织蛋白酶 B 被发现与鼠 B16 无黑色素瘤细胞的质膜/内体部分相关，具有三维图像分析的共聚焦显微镜表明组织蛋白酶 B 与外部基底细胞表面相关，这与其所提出的细胞外基质蛋白降解作用一致。我们从小鼠肝脏和 B16 无黑色素瘤细胞的匀浆以及 B16 肿瘤细胞的溶酶体和膜/内体部分中纯化并部分表征了组织蛋白酶 B。通过还原条件下的 SDS-PAGE，从肿瘤匀浆中纯化的组织蛋白酶 B 被解析为 M-r 31 000 的单个蛋白条带，对应于组织蛋白酶 B 的单链形式，相反，从肝匀浆中的组织蛋白酶 B 被解析为 M-r 31 000 和 24 000 的两条条带，分别对应于双链形式的单链和重链，肿瘤组织蛋白酶 B组织蛋白酶 B 由 4 个同工酶组成，pls 为 5.64、5.33、5.2 和 5.1，而肝脏组织蛋白酶 B 由 5 个同工酶组成，pls 为 5.64、5.5、5.45、5.35 和 5.3。 B16 肿瘤中额外的组织蛋白酶 B 酸性亚型可能反映了肿瘤中糖基化的改变。 B16 质膜/内体和溶酶体部分中异构体的共性表明组织蛋白酶 B 从溶酶体逆行运输至内体及其胞吐释放导致组织蛋白酶 B 与肿瘤细胞膜结合。
The lysosomal cysteine peptidase cathepsin B was found to be associated with plasma membrane/endosomal fractions of murine B16 amelanotic melanoma cells, Confocal microscopy with three dimensional image analysis indicated that cathepsin B was associated with the external basal cell surface, which would be consistent with its proposed role in degradation of extracellular matrix proteins. We purified and partially characterized cathepsin B from homogenates of murine liver and B16 amelanotic melanoma cells and from lysosomal and membrane/endosomal fractions of the B16 tumor cells. By SDS-PAGE under reducing conditions, the purified cathepsin B from the tumor homogenates was resolved as a single protein band of M-r 31 000, corresponding to the single chain form of cathepsin B, In contrast, cathepsin B from liver homogenates was resolved as two bands of M-r 31 000 and 24 000, corresponding to the single chain and the heavy chain of the double chain form, respectively, The tumor cathepsin B consisted of four isozymes with pls of 5.64, 5.33, 5.2 and 5.1, whereas the liver cathepsin B consisted of five isozymes with pls of 5.64, 5.5, 5.45, 5.35 and 5.3. The additional acidic isoforms of cathepsin B in the B16 tumor probably reflect altered glycosylation in tumors. The commonality of isoforms in the B16 plasma membrane/endosomal and lysosomal fractions suggests that retrograde trafficking of cathepsin B from the lysosome to the endosome and its exocytotic release result in the association of cathepsin B with the tumor cell membrane.