Zone J J, Taylor T B, Meyer L J, Petersen M J
Section of Dermatology, Salt Lake City Veterans Affairs Medical Center, Utah, USA.
J Invest Dermatol. 1998 Mar;110(3):207-10. doi: 10.1046/j.1523-1747.1998.00129.x.
IgA autoantibodies from the sera of some patients with linear IgA bullous dermatosis (LABD) recognize a 97 kDa antigen (LABD97) located in the lamina lucida of the basement membrane zone. As LABD autoantibodies do not react with the 180 and 230 kDa proteins recognized by bullous pemphigoid autoantibodies, LABD97 has been thought to represent a separate lamina lucida protein. In this study, we purified LABD97 from the extract of human epidermis using a monoclonal antibody immunoaffinity column and analyzed the amino acid sequence of the N terminus of purified LABD97. This revealed a 16 amino acid sequence that was identical to a previously reported sequence of the 180 kDa antigen in bullous pemphigoid (BPAg2). The N terminus was located 41 amino acids downstream from the carboxyl end of the transmembrane domain of BPAg2 and 11 amino acids downstream from the MCW-1 domain, the predominant bullous pemphigoid epitope. Purified LABD97 was subsequently enzymatically digested with endoproteinase Arg C and separated by chromatography, which resulted in multiple peptide fractions. Fourteen of these fractions were subjected to amino acid sequencing. The amino acid sequence of the peptide fractions, totaling 205 amino acids, were identical to sequences contained within the extracellular domain of BPAg2. Whereas the predominant epitope identified with bullous pemphigoid sera is located in the noncollagenous region of this protein, the epitope recognized by LABD sera is either within or adjacent to the collagenous portion. We conclude that LABD97 represents a portion of the extracellular domain of BPAg2 and that the IgA autoantibodies are directed against an epitope within or adjacent to a collagenous domain.
一些线状IgA大疱性皮肤病（LABD）患者血清中的IgA自身抗体可识别位于基底膜带透明层的一种97 kDa抗原（LABD97）。由于LABD自身抗体不与大疱性类天疱疮自身抗体识别的180 kDa和230 kDa蛋白发生反应，LABD97被认为代表一种独立的透明层蛋白。在本研究中，我们使用单克隆抗体免疫亲和柱从人表皮提取物中纯化了LABD97，并分析了纯化的LABD97 N端的氨基酸序列。结果显示一个16个氨基酸的序列，与先前报道的大疱性类天疱疮中180 kDa抗原（BPAg2）的序列相同。N端位于BPAg2跨膜结构域羧基末端下游41个氨基酸处，以及主要的大疱性类天疱疮表位MCW-1结构域下游11个氨基酸处。随后，纯化的LABD97用内肽酶Arg C进行酶切并通过色谱分离，得到多个肽段。其中14个肽段进行了氨基酸测序。这些肽段的氨基酸序列总共205个氨基酸，与BPAg2细胞外结构域内的序列相同。虽然大疱性类天疱疮血清识别的主要表位位于该蛋白的非胶原区域，但LABD血清识别的表位位于胶原部分内或与之相邻。我们得出结论，LABD97代表BPAg2细胞外结构域的一部分，并且IgA自身抗体针对的是胶原结构域内或与之相邻的一个表位。
