The human A33 antigen is a transmembrane glycoprotein and a novel member of the immunoglobulin superfamily
The human A33 antigen is a transmembrane glycoprotein and a novel member of the immunoglobulin superfamily
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DOI：
10.1073/pnas.94.2.469
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发表时间：
1997-01-21
影响因子：
11.1
通讯作者：
Burgess, AW
中科院分区：
文献类型：
--
作者：
Heath, JK;White, SJ;Burgess, AW
mAb A33检测在正常人结肠和小肠上皮和>95%的人结肠癌中表达的膜抗原，其在大多数其他人组织和肿瘤类型中不存在，鼠A33 mAb已在临床试验中显示靶向结肠癌，并且目前正在评估人源化抗体的治疗潜力。使用高度表达该抗原的人结肠癌细胞系LIM 1215和SW 1222的去污剂提取物，纯化该分子，产生43-kDa蛋白。测定N-末端序列，并在酶切后进一步获得内部肽序列。在PCR中使用简并引物以产生探针来筛选LIM 1215 cDNA文库，产生克隆，使我们能够推导出A33抗原的完整氨基酸序列并表达蛋白质。已经搜索了可用的数据库，并显示与已知蛋白质没有总体序列相似性。基于亲水性图，A33蛋白具有三个不同的结构域：213个氨基酸的胞外区（通过保守残基的序列比对，其含有两个推定的免疫球蛋白样结构域）、单个疏水跨膜结构域和含有四个连续半胱氨酸残基的高极性细胞内尾，这些数据表明A33抗原是免疫球蛋白超家族中的一种新的细胞表面受体或细胞粘附分子。
The mAb A33 detects a membrane antigen that is expressed in normal human colonic and small bowel epithelium and >95% of human colon cancers, It is absent from most other human tissues and tumor types, The murine A33 mAb has been shown to target colon cancer in clinical trials, and the therapeutic potential of a humanized antibody is currently being evaluated. Using detergent extracts of the human colon carcinoma cell lines LIM1215 and SW1222, in which the antigen is highly expressed, the molecule was purified, yielding a 43-kDa protein, The N-terminal sequence was determined and further internal peptide sequence obtained following enzymatic cleavage, Degenerate primers were used in PCRs to produce a probe to screen a LIM1215 cDNA library, yielding clones that enabled us to deduce the complete amino acid sequence of the A33 antigen and express the protein. The available data bases have been searched and reveal no overall sequence similarities with known proteins. Based on a hydrophilicity plot, the A33 protein has three distinct structural domains: an extracellular region of 213 amino acids (which, by sequence alignment of conserved residues, contains two putative immunoglobulin-like domains), a single hydrophobic transmembrane domain, and a highly polar intracellular tail containing four consecutive cysteine residues, These data indicate that the A33 antigen is a novel cell surface receptor or cell adhesion molecule in the immunoglobulin superfamily.