Ro/SS-A (52 kDa)

 Ro/SS-A (52 kDa)

Diseases:
Systemic Lupus Erythematosus (SLE)
Sjøgren Syndrome, Subacute Cutaneous LE
 

The Ro/SS-A antigen is a ribonucleoprotein complex and consists of two major proteins of 52 and 60 kDa, complexed with one specific RNA chain (either hY1, hY2, hY3 or hY5, which all are transcripts of RNA polymerase III); the Ro/SS-A (60 kDa) protein is the RNA-binding protein in the complex. The cellular function of this complex is still unresolved, as is the question whether the antigen is primarily located in the cytoplasm or in the nucleus or even shuttles between the 2 compartments. The Ro complex has recently been implicated in small RNA quality control and the enhancement of cell survival following exposure to ultraviolet irradiation.

Ro/SS-A antibodies occur with a prevalence of 60-90% in Sjøgren syndrome patients, but also with a prevalence of 25-50% in SLE patients and higher prevalences in subacute cutaneous LE patients. Neonatal lupus syndrome (congenital heart block, photosensitivity, skin lesions) is also associated with the presence of Ro/SS-A autoantibodies in the maternal and neonatal sera, in particular when these autoantibodies are directed to the 52-kDa antigen. There is a high risk of neonatal lupus if the mother is positive for Ro/SS-A (52 kDa) and La/SS-B antibodies. It should be noted that preparation of native Ro complexes from natural sources often contain substoichiometric and variable amounts of Ro/SS-A (52 kDa) protein, which complicates the detection of autoantibodies against the 52 kDa antigen and points to the usefulness of the recombinant Ro/SS-A (52 kDa) antigen.

Ro/SS-A (52 kDa) protein from DIARECT is expressed in the baculovirus expression system. Ro/SS-A (60 kDa), the other protein subunit of the complex, has recently become available in DIARECTs antigen panel as recombinant human antigen as well as highly purified natural antigen isolated from calf thymus.
 

相关疾病：系统性红斑狼疮（SLE），干燥综合征，亚急性皮肤型红斑狼疮Ro/SS-A抗原是一个核糖体核蛋白复合体，包含两个主要的蛋白，分子量分别为52和60kDa，与一个特异RNA链（hY1, hY2, hY3 或hY5中的任一个。它们都是RNA聚合酶III的转录物）复合；Ro/SS-A（60kDa）在复合物中是RNA结合蛋白。这个复合物的细胞功能还未了解，抗原初始是位于胞质或核内，或是在这两个空间中穿梭都还存在疑问。Ro复合物近来被发现与小RNA质量控制和细胞受到紫外线照射后的生存率增强有关。Ro/SS-A抗体存在于60-90%的干燥综合征患者当中，及25-50%的SLE的患者中，在亚急性皮肤型红斑狼疮患者中的存在率还要更高些。新生儿红斑狼疮（先天性心脏传导阻滞）也同样与母体和新生儿中Ro/SS-A自身抗体的存在相关，特别是当这些自身抗体指向52kD的抗原时。如果母亲的Ro/SS-A (52 kDa)和 La/SS-B抗体是阳性，那么新生儿患新生儿红斑狼疮的风险就非常高。值得注意的是从天然来源获得的天然Ro复合物通常有亚化学计量的可变Ro/SS-A(52kD)蛋白，它会使抗52kDa抗原的自身抗体检测变得复杂，这说明了重组Ro/SS-A (52 kDa)抗原的实用性。

DIARECT生产的Ro/SS-A (52 kDa)蛋白在杆状病毒表达系统中表达。Ro/SS-A (60 kDa)，这个复合物的另一个亚基 也可以在DIARECT订购天然的和重组的两种形式。