Gorvel J P, Rigal A, Bernadac A, Maroux S
Eur J Biochem. 1986 Sep 15;159(3):499-505. doi: 10.1111/j.1432-1033.1986.tb09914.x.
Mouse 23 B 921 monoclonal antibody recognized a rabbit brush-border antigen with an apparent molecular mass 140 kDa (140-kDa Ag) which, unlike most hydrolases, is expressed in the poorly differentiated crypt cells of the small intestine. Immunoelectron microscopy of brush-border vesicles showed that the 23 B 921 bound to an epitope localized on the outside of the membrane. As is the case with hydrolases the external domain of the 140-kDa Ag constitutes the main part of the molecule, which can be released by papain treatment of brush-border vesicles. The presence of a small hydrophobic domain, anchoring the molecule into the membrane and responsible for its amphipatic character, was shown by its affinity for Triton-X114 micelles. The topological organization in the membrane of 140-kDa Ag seemed to be identical to that of hydrolases. Unlike hydrolases, however, the native structure of the antigen was found from its sensitivity to proteolysis to be very dependent on its integration into the lipid bilayer. Nevertheless, detergent-extracted 140-kDa Ag can be purified by immunoaffinity chromatography although it cannot be stocked for more than 48 h even in the presence of protease inhibitors. The carbohydrate moiety of 140-kDa Ag, bearing the human blood group A determinant, amounts to 20% of the total molecular mass. The existence of some privileged relationship was established between 140-kDa Ag and hydrolases: in the membrane, hydrolases protect the 140-kDa Ag from papain action; after detergent extraction, 140-kDa Ag is strongly associated with several hydrolases particularly disaccharidases.
小鼠23 B 921单克隆抗体识别一种兔刷状缘抗原，其表观分子量为140 kDa（140 kDa抗原），与大多数水解酶不同，该抗原在小肠分化不良的隐窝细胞中表达。刷状缘小泡的免疫电子显微镜显示，23 B 921与位于膜外侧的一个表位结合。与水解酶一样，140 kDa抗原的胞外结构域构成分子的主要部分，该部分可通过木瓜蛋白酶处理刷状缘小泡而释放。通过其对Triton-X114胶束的亲和力表明，存在一个小的疏水域，将该分子锚定在膜中并赋予其两亲性。140 kDa抗原在膜中的拓扑结构似乎与水解酶相同。然而，与水解酶不同的是，从其对蛋白水解的敏感性发现，该抗原的天然结构非常依赖于其整合到脂质双层中。尽管如此，去污剂提取的140 kDa抗原可通过免疫亲和层析纯化，尽管即使存在蛋白酶抑制剂，其储存时间也不能超过48小时。140 kDa抗原的碳水化合物部分带有人类A血型决定簇，占总分子量的20%。在140 kDa抗原与水解酶之间建立了一些特殊关系：在膜中，水解酶可保护140 kDa抗原免受木瓜蛋白酶作用；去污剂提取后，140 kDa抗原与几种水解酶特别是双糖酶紧密相关。
