TRA98 is a rat monoclonal antibody (mAb) which recognizes a specific antigen in the nuclei of germ cells. mAb TRA98 has been used to understand the mechanism of germ cell development and differentiation in many studies. In mice, the antigen recognized by mAb TRA98 or GCNA1 has been reported to be a GCNA gene product, but despite the demonstration of the immunoreactivity of this mAb in human testis and sperm in 1997, the antigen in humans remains unknown, as of date. To identify the human antigen recognized by mAb TRA98, a human comprehensive wet protein array was developed containing 19,446 proteins derived from human cDNAs. Using this array, it was found that the antigen of mAb TRA98 is not a GCNA gene product, but nuclear factor‐κB activating protein (NKAP). In mice, mAb TRA98 recognized both the GCNA gene product and NKAP. Furthermore, conditional knockout of Nkap in mice revealed a phenotype of Sertoli cell‐only syndrome. Although NKAP is a ubiquitously expressed protein, NKAP recognized by mAb TRA98 in mouse testis was SUMOylated. These results suggest that NKAP undergoes modifications, such as SUMOylation in the testis, and plays an important role in spermatogenesis.

中文翻译：

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使用人类综合湿蛋白阵列对生殖细胞单克隆抗体TRA98识别的抗原进行鉴定和表征

TRA98是大鼠单克隆抗体（mAb），可识别生殖细胞核中的特定抗原。在许多研究中，mAb TRA98已用于了解生殖细胞发育和分化的机制。据报道，在小鼠中，mAb TRA98或GCNA1识别的抗原是GCNA基因产物，尽管该mAb在1997年在人的睾丸和精子中具有免疫反应性，但迄今为止，人中的抗原仍是未知的。为了鉴定被mAb TRA98识别的人类抗原，开发了人类综合湿蛋白阵列，其中包含19446种衍生自人类cDNA的蛋白质。使用该阵列，发现mAb TRA98的抗原不是GCNA基因产物，而是核因子-κB活化蛋白（NKAP）。在小鼠中，mAb TRA98可识别GCNA基因产物和NKAP。此外，小鼠的Nkap显示了Sertoli-only综合征的表型。尽管NKAP是一种普遍表达的蛋白，但小鼠睾丸中被mAb TRA98识别的NKAP被SUMOylated了。这些结果表明，NKAP进行了修饰，例如睾丸中的SUMOylation，并在精子发生中起重要作用。