Koyama Y, Yang H M, Wargalla U, Reisfeld R A, Harper J R
Department of Immunology, Research Institute of Scripps Clinic, La Jolla, California 92037.
J Biol Chem. 1988 Jan 15;263(2):806-11.
A murine monoclonal antibody (mAb A23-16) was produced that recognizes a glycoprotein antigen preferentially expressed on the surface of human small cell lung carcinoma cells. This antibody is of IgG 1 isotype, has an association constant of 5 x 10(7) M-1, and reacts preferentially with human small cell lung carcinoma cell lines and fresh frozen sections in enzyme-linked immunosorbent assays and immunoperoxidase assays, respectively. The antigen recognized by A23-16 is a sulfated glycoprotein with phosphorylated threonine residues. The mature 90-kDa molecule has intrachain disulfide bonds and appears to be derived from a 76-kDa precursor, that is neither sulfated nor phosphorylated, but contains N-linked oligosaccharides. Conversion of the 76-kDa precursor to the mature form is accompanied by processing of these oligosaccharides from the high mannose to the complex type, although the increase in molecular mass from 76 to 90 kDa cannot be accounted for by this modification alone. MAb A23-16 reacts with its target antigen independent of the N-linked oligosaccharides, but requires intact intrachain disulfide bond(s) for reactivity. These studies on the molecular characterization of a monoclonal antibody-defined glycoprotein, preferentially expressed by small cell lung cancer, provide a basis for further structural and functional studies that may eventually lead to a delineation of its biological relevance for neoplastic transformation.
制备了一种鼠单克隆抗体（mAb A23-16），它识别一种优先在人小细胞肺癌细胞表面表达的糖蛋白抗原。该抗体为IgG 1同种型，缔合常数为5×10⁷ M⁻¹，分别在酶联免疫吸附测定和免疫过氧化物酶测定中优先与人小细胞肺癌细胞系和新鲜冰冻切片发生反应。A23-16识别的抗原是一种带有磷酸化苏氨酸残基的硫酸化糖蛋白。成熟的90 kDa分子具有链内二硫键，似乎源自一种76 kDa的前体，该前体既不硫酸化也不磷酸化，但含有N-连接寡糖。76 kDa前体向成熟形式的转变伴随着这些寡糖从高甘露糖型加工为复合型，尽管从76 kDa到90 kDa的分子量增加不能仅由这种修饰来解释。MAb A23-16与其靶抗原反应，不依赖于N-连接寡糖，但反应需要完整的链内二硫键。这些关于一种由小细胞肺癌优先表达的单克隆抗体定义的糖蛋白的分子特征研究，为进一步的结构和功能研究提供了基础，这些研究最终可能导致阐明其与肿瘤转化的生物学相关性。
