The pSTBlue-1 AccepTor™ vector kits are designed to simplify the PCR cloning process by using non-proofreading thermostable DNA polymerases (eg. KOD XL polymerase and native and recombinant Taq polymerases), which leave single 3'-dA overhangs on the reaction products. The AccepTor™ vectors enable direct ligation by virtue of single 3'-dU overhangs that anneal efficiently with 3'-dA extensions on PCR products. The dU residues are converted to dT residues in vivo following transformation.