Kikumoto Y, Oka T, Cao J N, Sze L, Irie R F
John Wayne Cancer Institute, Santa Monica, California 90404, USA.
Hybridoma. 1995 Feb;14(1):45-50. doi: 10.1089/hyb.1995.14.45.
A human B lymphoblastoid cell line JWCI-L94 secretes an IgM human monoclonal antibody (HuMAb) that reacts with human melanoma cell lines, M14 and M12. To identify the antigenic epitope of this antibody, we screened lambda gt11 expression libraries constructed from M14 and M12. A total of 12 immunoreactive clones were isolated, and their DNA sequences were determined. The only sequence shared by all these clones was alanine-proline (A-P) at the carboxyl (C) terminal. HuMAb L94 reacted not only with C-terminal A-P-containing fusion proteins, but also with the synthetic dipeptide A-P. None of the peptides containing A-P internally or amino terminally reacted to HuMAb L94. Proline or alanine alone had no ability to bind to HuMAb L94. When alanine was replaced by glycine (G-P) or proline (P-P), the binding activity of these peptides was similar to that of A-P. On the other hand, when alanine was replaced by serine, valine, leucine, glutamine, lysine, methionine, phenylalanine, or hydroxyl proline, the resulting peptide completely lost the antigenic activity of HuMAb L94. These results demonstrate that HuMAb L94 recognizes C-terminal A-P, G-P, or P-P, and that a human antibody can recognize peptides as small as a two-amino acid residue.
一种人B淋巴母细胞系JWCI-L94分泌一种IgM人单克隆抗体（HuMAb），该抗体可与人黑色素瘤细胞系M14和M12发生反应。为了鉴定该抗体的抗原表位，我们筛选了由M14和M12构建的λgt11表达文库。共分离出12个免疫反应性克隆，并测定了它们的DNA序列。所有这些克隆共有的唯一序列是羧基（C）末端的丙氨酸-脯氨酸（A-P）。HuMAb L94不仅与含C末端A-P的融合蛋白反应，还与合成二肽A-P反应。内部或氨基末端含A-P的肽均不与HuMAb L94反应。单独的脯氨酸或丙氨酸没有结合HuMAb L94的能力。当丙氨酸被甘氨酸（G-P）或脯氨酸（P-P）取代时，这些肽的结合活性与A-P相似。另一方面，当丙氨酸被丝氨酸、缬氨酸、亮氨酸、谷氨酰胺、赖氨酸、甲硫氨酸、苯丙氨酸或羟脯氨酸取代时，所得肽完全丧失了HuMAb L94的抗原活性。这些结果表明，HuMAb L94识别C末端的A-P、G-P或P-P，并且人抗体可以识别小至两个氨基酸残基的肽。
