The Structure and Function of the 450-kDa Autoantigen Expressed in Keratinocytes

我们之前报告了一例临床和病理上与大疱性类天疱疮相似的表皮下水泡性疾病。免疫印迹分析显示，患者的血清不与230或180 kDa的大疱性类天疱疮抗原反应，但仅识别450 kDa的表皮多肽。为了阐明该抗原的分子结构，我们克隆了重叠的cDNA并对其进行了鉴定。共分离到约13.8kb的cDNAs，占全长的90%。该基因与plectin有同源性，命名为plectin 2。以此为探针，对人基因组文库进行筛选，分离到4个重叠克隆。在该基因10kb的3‘端，未发现内含子。结合来自cDNA和基因的信息，在该分子的羧基末端有四个高度同源的重复序列，由534个氨基酸组成。因此，果胶凝集素2是一种来源于不同于果胶编码基因的独特基因的分子。

We previously reported an individual with subepidermal blistering disease that resembled bullous pemphigoid both clinically and pathologically. Immunoblot analysis revealed that the patient's serum did not react with the 230- or 180-kDa bullous pemphigoid antigens, but recognized exclusively a 450-kDa epidermal polypeptide. To elucidate the molecular structure of this antigen, we have cloned and characterized the overlapping cDNAs. About 13.8kb cDNAs, covering 90% of total length, were isolated. It has homology with plectin and it was named plectin 2. Using the cDNAs as probes, human genomic library was screened and four overlapping clones were isolated. At 3' end of 10kb in the gene, no intron was found. Combined with the information from the cDNAs and the gene, four highly homologous repeats, composed of 534 amino acids, located at the carboxy terminal end of this molecule. As a result, plectin 2 is the molecule derived from the unique gene which differ from that encodes pectin.