DNA replication is initiated upon binding of "initiators" to origins of replication. In simian virus 40 (SV40). the core origin contains four pentanucleotide binding sites organized as pairs of inverted repeats. Here we describe the crystal structures of the origin binding domain (obd) of the SV40 large T-antigen (T-ag) both with and without a subfragment of origin-containing DNA. https://jalyttlers.shop/product-category/foodcover/