Keshav K F, Chen C, Dutta A
Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
Mol Cell Biol. 1995 Jun;15(6):3119-28. doi: 10.1128/MCB.15.6.3119.
Replication protein A (RPA) is a complex of three polypeptides of 70, 34, and 13 kDa isolated from diverse eukaryotes. The complex is a single-stranded DNA-binding protein essential for simian virus 40-based DNA replication in vitro and for viability in the yeast Saccharomyces cerevisiae. We have identified a new 30-kDa human protein which interacts with the 70- and 13-kDa subunits of RPA, with a yeast two-hybrid/interaction trap method. This protein, Rpa4, has 47% identity with Rpa2, the 34-kDa subunit of RPA. Rpa4 associates with the 70- and 13-kDa subunits to form a trimeric complex capable of binding to single-stranded DNA. Rpa4 is preferentially expressed in placental and colon mucosa tissues. In the placenta, Rpa4 is more abundant than the 70-kDa Rpa1 subunit and is not associated with either Rpa1 or with any other single-stranded DNA-binding protein. In proliferating cells in culture, Rpa4 is considerably less abundant than Rpa1 and Rpa2. Northern (RNA) blot analysis suggest that there are alternatively processed forms of the RPA4 mRNA, and Southern blot analysis indicates that beside RPA4 there may be other members of the RPA2 gene family.
复制蛋白A（RPA）是一种由70 kDa、34 kDa和13 kDa三种多肽组成的复合物，从多种真核生物中分离得到。该复合物是一种单链DNA结合蛋白，对体外基于猿猴病毒40的DNA复制以及酿酒酵母的生存能力至关重要。我们利用酵母双杂交/相互作用陷阱方法鉴定出一种新的30 kDa人类蛋白，它与RPA的70 kDa和13 kDa亚基相互作用。这种蛋白Rpa4与RPA的34 kDa亚基Rpa2有47%的同源性。Rpa4与70 kDa和13 kDa亚基结合形成一种能够结合单链DNA的三聚体复合物。Rpa4在胎盘和结肠黏膜组织中优先表达。在胎盘中，Rpa4比70 kDa的Rpa1亚基更丰富，并且不与Rpa1或任何其他单链DNA结合蛋白相关联。在培养的增殖细胞中，Rpa4的丰度远低于Rpa1和Rpa2。Northern（RNA）印迹分析表明RPA4 mRNA存在可变加工形式，Southern印迹分析表明除RPA4外，RPA2基因家族可能还有其他成员。
