Larocca D, Peterson J A, Ceriani R L
John Muir Cancer and Aging Research Institute, Walnut Creek, CA 94596.
Hybridoma. 1992 Apr;11(2):191-201. doi: 10.1089/hyb.1992.11.191.
The high molecular weight mucin found in human milk fat globule and on the surface of mammary and other epithelial cells contains a 20 amino acid tandem repeat sequence that is highly immunogenic. We have immunoscreened lambda gt11 cDNA expression libraries from MCF7 cells and lactating breast tissue with 5 anti-mucin monoclonal antibodies. We isolated a group of cDNA clones that had the repeat sequence (HB11-2, HB11-6, HB11-10) and a group that had little or no homology with the repeat sequence (NP4, NP5, HB11-4). A fusion protein produced by NP4 bound preferentially BrE2, while HB11-4 bound only BrE2 and BrE3, NP5 produced a fusion protein that bound only Mc5 and not the other MAbs. Sequencing of the NP5 cDNA revealed it to be distinct from the mucin sequence and instead to have 97% identity with the estrogen induced transcript, pS2. An alternate reading frame was translated by the lambda gt11 fusion gene yielding a 44 amino acid protein having no homology with pS2 protein. Only a short region of homology (5 amino acids) with the breast mucin tandem repeat was found which was shown to be a mimotope for the Mc5 epitope on the breast mucin. High level expression of the NP5 cDNA was achieved by subcloning it into pEX2. The NP5 fusion protein has been useful for developing an assay for the presence of mucin derived antigen in patient serum.
在人乳脂肪球以及乳腺和其他上皮细胞表面发现的高分子量粘蛋白含有一个20个氨基酸的串联重复序列，该序列具有高度免疫原性。我们用5种抗粘蛋白单克隆抗体对来自MCF7细胞和泌乳乳腺组织的λgt11 cDNA表达文库进行了免疫筛选。我们分离出了一组具有重复序列的cDNA克隆（HB11-2、HB11-6、HB11-10）和一组与重复序列几乎没有同源性或无同源性的克隆（NP4、NP5、HB11-4）。由NP4产生的融合蛋白优先结合BrE2，而HB11-4仅结合BrE2和BrE3，NP5产生的融合蛋白仅结合Mc5，而不结合其他单克隆抗体。NP5 cDNA的测序显示它与粘蛋白序列不同，而是与雌激素诱导转录本pS2有97%的同一性。λgt11融合基因翻译出一个替代阅读框，产生一种与pS2蛋白无同源性的44个氨基酸的蛋白质。仅发现与乳腺粘蛋白串联重复序列有一个短的同源区域（5个氨基酸），该区域被证明是乳腺粘蛋白上Mc5表位的模拟表位。通过将NP5 cDNA亚克隆到pEX2中实现了其高水平表达。NP5融合蛋白已被用于开发一种检测患者血清中粘蛋白衍生抗原的方法。
