Nonaka S, Ishiko A, Masunaga T, Akiyama M, Owaribe K, Shimizu H, Nishikawa T
Department of Dermatology, Keio University School of Medicine, Tokyo, Japan.
J Invest Dermatol. 2000 Nov;115(5):889-92. doi: 10.1046/j.1523-1747.2000.00136.x.
The 180 kDa bullous pemphigoid antigen is a hemidesmosome-associated transmembranous protein with a molecule length estimated to be 190-230 nm, which is much longer than the transverse length of the lamina lucida and lamina densa. The purpose of this study was to clarify the precise in vivo structure of the 180 kDa bullous pemphigoid antigen in normal human skin. We used three monoclonal antibodies directed to (i) the intracellular globular head of the 180 kDa bullous pemphigoid antigen, (ii) the mid-portion of the flexible tail of the antigen, corresponding approximately to amino acids 1000-1320, and (iii) the carboxyl terminal end, corresponding approximately to amino acids 1320-1500 of the antigen. Using low temperature postembedding immunoelectron microscopy, we quantitated the distribution of immunogold labeling of these monoclonal antibodies in normal human skin. The results showed that the monoclonal antibodies (i) bound to the intracellular portion of the hemidesmosome at a mean distance of 20 nm from the plasma membrane, (ii) bound to the lamina densa beneath the hemidesmosome at a mean distance of 65 nm from the plasma membrane, and (iii) bound to the lamina densa-lamina lucida interface at a mean distance of 39 nm from the plasma membrane. Considering the reported size of the 180 kDa bullous pemphigoid antigen, our results indicate that the extracellular domain of the antigen has at least one loop structure in the lamina densa in vivo. This unique structure of the antigen is thought to contribute to dermo- epidermal adhesion by intertwining with other basement membrane components.
180kDa大疱性类天疱疮抗原是一种与半桥粒相关的跨膜蛋白，其分子长度估计为190 - 230nm，远长于透明层和致密层的横向长度。本研究的目的是阐明180kDa大疱性类天疱疮抗原在正常人体皮肤中的精确体内结构。我们使用了三种单克隆抗体，分别针对：（i）180kDa大疱性类天疱疮抗原的细胞内球状头部；（ii）抗原柔性尾部的中部，大致对应于氨基酸1000 - 1320；（iii）抗原的羧基末端，大致对应于氨基酸1320 - 1500。通过低温包埋后免疫电子显微镜技术，我们定量了这些单克隆抗体在正常人体皮肤中的免疫金标记分布。结果显示，单克隆抗体（i）在距质膜平均20nm处与半桥粒的细胞内部分结合；（ii）在距质膜平均65nm处与半桥粒下方的致密层结合；（iii）在距质膜平均39nm处与致密层 - 透明层界面结合。考虑到已报道的180kDa大疱性类天疱疮抗原的大小，我们的结果表明该抗原的细胞外结构域在体内致密层中至少有一个环结构。抗原的这种独特结构被认为通过与其他基底膜成分缠绕来促进真皮 - 表皮黏附。
