Lefèvre A, Martin Ruiz C, Chokomian S, Duquenne C, Finaz C
Institut Fédératif de Recherche sur les Cyokines Paris Sud, INSERM/CNRS, Clamart, France.
Mol Hum Reprod. 1997 Jun;3(6):507-16. doi: 10.1093/molehr/3.6.507.
G12 monoclonal antibody (mAb), one of a library of constructed mAb directed against human sperm proteins, was found by immunoperoxidase staining to label the post-acrosomal and neck regions of fixed human cauda epididymal and ejaculated spermatozoa. Epithelium and fluid of caput epididymis were strongly labelled while there was no staining on testis and efferent ducts. Western lot analysis revealed that G12 antibody reacted with proteins of 17.5, 18 and 19 kDa in human spermatozoa. This pattern seems to be specific for mature human spermatozoa, as it has not been observed either in other human tissues tested, or in spermatozoa from different animals. SOB2, the corresponding protein, was isolated from NP40-extracted human spermatozoa by using preparative electrophoresis, followed by isoelectrofocusing according to its isoelectric point of 6.4 G12 Fab fragments strongly inhibited binding of human spermatozoa to zona-free hamster oocytes (up to 86% inhibition at 200 micrograms/ml). Impairment of binding was dependent on the concentration of purified G12 immunoglobulin (Ig)G1, and significant even at 10 micrograms/ml. There was no inhibitory effect of G12 antibody on sperm motility parameters or triggering of the acrosome reaction and it did not inhibit binding to human zona pellucida. These results indicate that SOB2 is likely to participate in membrane oocyte binding, and my be potential candidate for the development of a contraceptive vaccine.
G12单克隆抗体（mAb）是针对人类精子蛋白构建的单克隆抗体文库中的一种，通过免疫过氧化物酶染色发现，它可标记固定后的人类附睾尾精子和射出精子的顶体后区及颈部区域。附睾头的上皮和液体被强烈标记，而睾丸和输出小管未出现染色。蛋白质免疫印迹分析显示，G12抗体与人类精子中17.5、18和19 kDa的蛋白质发生反应。这种模式似乎是成熟人类精子所特有的，因为在其他测试的人体组织或不同动物的精子中均未观察到。通过制备性电泳从NP40提取的人类精子中分离出相应的蛋白质SOB2，然后根据其6.4的等电点进行等电聚焦。G12 Fab片段强烈抑制人类精子与去透明带仓鼠卵母细胞的结合（在200微克/毫升时抑制率高达86%）。结合的受损程度取决于纯化的G12免疫球蛋白（Ig）G1的浓度，即使在10微克/毫升时也有显著抑制作用。G12抗体对精子活力参数或顶体反应的触发没有抑制作用，也不抑制与人类透明带的结合。这些结果表明，SOB2可能参与膜-卵母细胞结合，可能是开发避孕疫苗的潜在候选物。
