该基因编码异三聚体复制蛋白A（RPA）复合物的最大亚单位，与单链DNA（SSDNA）结合，形成核蛋白复合物，在DNA代谢中起重要作用，参与DNA复制、修复、重组、端粒维持，并通过激活共济失调毛细血管扩张症和RAD3相关蛋白（ATR）激酶来协调细胞对DNA损伤的反应。核蛋白复合物保护单链dna免受核酸酶的侵害，防止形成干扰修复的二级结构，并协调不同基因组维持因子的募集和离开。该亚单位包含四个寡核苷酸/寡糖结合（ob）结构域，尽管大多数ssdna结合发生在其中两个结构域中。异三聚体复合物具有两种不同的ssdna结合模式：低亲和力和高亲和力，这两种模式决定了ssdna结合域的利用。不同的结合方式在dna结合的长度和与之相互作用的蛋白质上不同，从而在调控不同的基因组维持途径中发挥作用。[由RefSeq提供，2017年9月]
This gene encodes the largest subunit of the heterotrimeric Replication Protein A (RPA) complex, which binds to single-stranded DNA (ssDNA), forming a nucleoprotein complex that plays an important role in DNA metabolism, being involved in DNA replication, repair, recombination, telomere maintenance, and co-ordinating the cellular response to DNA damage through activation of the ataxia telangiectasia and Rad3-related protein (ATR) kinase. The nucleoprotein complex protects the single-stranded DNA from nucleases, prevents formation of secondary structures that would interfere with repair, and co-ordinates the recruitment and departure of different genome maintenance factors. This subunit contains four oligonucleotide/oligosaccharide-binding (OB) domains, though the majority of ssDNA binding occurs in two of these domains. The heterotrimeric complex has two different modes of ssDNA binding, a low-affinity and high-affinity mode, determined by which ssDNA binding domains are utilized. The different binding modes differ in the length of DNA bound and in the proteins with which it interacts, thereby playing a role in regulating different genomic maintenance pathways. [provided by RefSeq, Sep 2017]