Tasanen K, Eble J A, Aumailley M, Schumann H, Baetge J, Tu H, Bruckner P, Bruckner-Tuderman L
Department of Dermatology, University of Münster, 48149 Münster, Germany.
J Biol Chem. 2000 Feb 4;275(5):3093-9. doi: 10.1074/jbc.275.5.3093.
Collagen XVII is a hemidesmosomal transmembrane molecule important for epithelial adhesion in the skin. It exists in two forms, as a full-length protein and as a soluble ectodomain that is shed from the keratinocyte surface by furin-mediated proteolysis. To obtain information on the conformation and the functions of this unusual collagen, its largest collagenous domain, Col15, was expressed in a eukaryotic episomal expression system and purified by DEAE and fast protein liquid- Mono S chromatography. The protein was triple-helical (T(m) of 26.5 degrees C) when produced in cultures containing ascorbic acid. When the vitamin supply was limited, the 4-hydroxyproline content was reduced from 74 to 9%, which, in turn, resulted in a drastic reduction of the stability of the triple helix. The glycine substitution mutation G627V associated with junctional epidermolysis bullosa, a human blistering skin disease, also had a striking effect on thermal stability of rCol15 causing partial unfolding already at 4 degrees C. Col15 promoted cell adhesion of epithelial and fibroblastic cell lines with a beta1 integrin-mediated mechanism. In concert with this, in acquired autoimmune blistering skin diseases, circulating IgG and IgA autoantibodies were found to target rCol15r.
ⅩⅦ型胶原蛋白是一种半桥粒跨膜分子，对皮肤中的上皮黏附至关重要。它以两种形式存在，一种是全长蛋白，另一种是可溶性胞外结构域，该结构域通过弗林蛋白酶介导的蛋白水解作用从角质形成细胞表面脱落。为了获取有关这种特殊胶原蛋白的构象和功能的信息，其最大的胶原结构域Col15在真核游离表达系统中表达，并通过DEAE和快速蛋白质液相-单S色谱法进行纯化。当在含有抗坏血酸的培养物中产生时，该蛋白呈三螺旋结构（熔解温度为26.5℃）。当维生素供应有限时，4-羟脯氨酸含量从74%降至9%，这反过来又导致三螺旋稳定性急剧下降。与交界性大疱性表皮松解症（一种人类水疱性皮肤病）相关的甘氨酸替代突变G627V，对重组Col15的热稳定性也有显著影响，在4℃时就已导致部分解折叠。Col15通过β1整合素介导的机制促进上皮细胞系和成纤维细胞系的细胞黏附。与此一致的是，在获得性自身免疫性水疱性皮肤病中，发现循环中的IgG和IgA自身抗体靶向重组Col15r。
